diff --git a/data/config.yaml b/data/config.yaml
index a46cec6..e2016e1 100644
--- a/data/config.yaml
+++ b/data/config.yaml
@@ -1,3 +1,4 @@
+experimental: False # should probably expand this into a dict of experimental flags
 sample_rate: 24_000 # 44_000 for dac
 audio_backend: "vocos" # or dac
 
@@ -11,9 +12,10 @@ models:
   tones: 1
   arch_type: llama
   training: True
-  version: 4
+  version: 5
   attention: flash_attention_2
   dropout: 0.1
+  experimental: False
 
   loss_factors:
     text: 0.1
@@ -63,11 +65,10 @@ trainer:
 
   keep_last_checkpoints: 4
 
-  aggressive_optimizations: False
-  load_disabled_engines: False
+  gradient_checkpointing: True
 
-  #load_state_dict: True
   strict_loading: False
+  #load_state_dict: True
   #load_tag: "9500"
   #load_states: False
   #restart_step_count: True
@@ -85,8 +86,6 @@ trainer:
 
     amp: False
 
-  activation_checkpointing: True
-
   load_webui: False
 
 inference:
@@ -109,8 +108,6 @@ optimizations:
   bitnet: False
   fp8: False
 
-experimental: True # practically required now it seems
-
 dataset:
   speaker_name_getter: "lambda p: f'{p.parts[-3]}_{p.parts[-2]}'"
   speaker_group_getter: "lambda p: f'{p.parts[-3]}'"
diff --git a/vall_e/config.py b/vall_e/config.py
index 4adf307..8f2d715 100755
--- a/vall_e/config.py
+++ b/vall_e/config.py
@@ -191,6 +191,7 @@ class Dataset:
 	def max_duration(self):
 		return self.duration_range[1]
 
+# I really need to clean this up
 @dataclass()
 class Model:
 	_max_levels: int = 0
@@ -215,6 +216,7 @@ class Model:
 	dropout: float = 0.1 # adjustable dropout value
 	loss_factors: dict = field(default_factory=lambda: { "text": 0.1, "prom": 0.0, "resp": 1.0 })
 	kv_heads: int = 0
+	experimental: bool = False
 
 	def get(self, name=None):
 		return [ self ] if not name or self.name == name else []
@@ -306,6 +308,10 @@ class Model:
 	def activation_checkpointing(self):
 		return cfg.trainer.activation_checkpointing
 	
+	@property
+	def gradient_checkpointing(self):
+		return cfg.trainer.gradient_checkpointing
+	
 @dataclass()
 class Hyperparameters:
 	batch_size: int = 8
@@ -519,7 +525,8 @@ class Trainer:
 	load_module_only: bool = False
 	restart_step_count: bool = False
 
-	activation_checkpointing: bool = True
+	activation_checkpointing: bool | None = None # deprecated
+	gradient_checkpointing: bool = True
 
 	aggressive_optimizations: bool = False
 	check_for_oom: bool = True
@@ -728,6 +735,9 @@ class Config(_Config):
 		if self.inference.audio_backend != "" and self.audio_backend == "":
 			self.audio_backend = self.inference.audio_backend
 
+		if self.trainer.activation_checkpointing is not None:
+			self.trainer.gradient_checkpointing = self.trainer.activation_checkpointing
+
 # Preserves the old behavior
 class NaiveTokenizer:
 	def get_vocab( self ):
diff --git a/vall_e/data.py b/vall_e/data.py
index 5a58f2f..734d178 100755
--- a/vall_e/data.py
+++ b/vall_e/data.py
@@ -24,11 +24,144 @@ from typing import Any
 from torch import Tensor
 from torch.utils.data import DataLoader, Dataset as _Dataset
 from torch.utils.data.distributed import DistributedSampler
+from torch.nn.utils.rnn import pad_sequence
+
 from tqdm.auto import tqdm
 # torch.multiprocessing.set_sharing_strategy("file_system")
 
 _logger = logging.getLogger(__name__)
 
+# fold into a typical LLM sequence (one embedding rather than split embeddings)
+def fold_inputs(
+	text_list = [],
+	prom_list = [],
+	resp_list = [],
+
+	ignore_index = None,
+
+	sep = 3,
+	stop = 3,
+	
+	text_tokens = 256,
+	audio_tokens = 1024,
+	audio_rvq_levels = cfg.model.prom_levels
+):
+	def _create_mask(l, device):
+		seq = torch.arange(max(l), device=device).unsqueeze(0)  # (1 t)
+		stop = torch.tensor(l, device=device).unsqueeze(1)  # (b 1)
+		return (seq < stop).float()  # (b t)
+
+	def list_to_tensor(x_list: list[Tensor]):
+		l = list(map(len, x_list))
+		x = pad_sequence(x_list).t()
+
+		m = _create_mask(l, x_list[0].device)
+		m = m.to(x)
+		return x, m
+
+	device = text_list[0].device
+	batch_size = len(text_list)
+	input_ids = [ [] for _ in range(batch_size) ]
+
+	offset = 0
+	
+	sep = torch.Tensor([ sep ])
+	stop = torch.Tensor([ stop ])
+
+	for i, text in enumerate(text_list):
+		seq = text.to("cpu", dtype=torch.int64)
+		input_ids[i].append( seq )
+		input_ids[i].append( sep )
+	
+	offset = text_tokens
+	for i, prom in enumerate(prom_list):
+		if ignore_index is not None:
+			seq = torch.Tensor( [ ignore_index for _ in range( prom.shape[0] * prom.shape[1] ) ] ).to("cpu", dtype=torch.int64)
+		else:
+			seq = prom.flatten().to("cpu", dtype=torch.int64)
+			for idx, token in enumerate( seq ):
+				token += offset + ( audio_tokens * ( idx % audio_rvq_levels ) )
+
+		input_ids[i].append( seq )
+		input_ids[i].append( sep )
+	
+	offset = text_tokens + (audio_tokens * audio_rvq_levels)
+	for i, resp in enumerate(resp_list):
+		seq = resp.flatten().to("cpu", dtype=torch.int64)
+		for idx, token in enumerate( seq ):
+			token += offset + ( audio_tokens * ( idx % audio_rvq_levels ) )
+		input_ids[i].append( seq )
+		input_ids[i].append( stop )
+
+	for i, batch in enumerate(input_ids):
+		input_ids[i] = torch.concat(input_ids[i], dim=-1).to(device=device, dtype=torch.int64)
+
+	return list_to_tensor(input_ids)
+
+# unfold from one unified token ID space to separate token spaces
+def unfold_outputs(
+	output_ids,
+
+	sep = 3,
+	stop = 3,
+	
+	text_tokens = 256,
+	audio_tokens = 1024,
+	audio_rvq_levels = cfg.model.prom_levels
+):
+	device = output_ids.device
+	batch_size = output_ids.shape[0]
+
+	text_list = [ [] for _ in range(batch_size) ]
+	prom_list = [ [] for _ in range(batch_size) ]
+	resp_list = [ [] for _ in range(batch_size) ]
+
+	for i, batch in enumerate( output_ids ):
+		for idx, token in enumerate( batch ):
+			id = token.item()
+			if id == sep or id == stop:
+				continue
+
+			if 0 <= id and id < text_tokens:
+				text_list[i].append( id )
+			elif text_tokens <= id and id < text_tokens + (audio_tokens * audio_rvq_levels):
+				prom_list[i].append( (id - text_tokens) % audio_tokens )
+			elif text_tokens + (audio_tokens * audio_rvq_levels) <= id:
+				resp_list[i].append( (id - text_tokens) % audio_tokens )
+
+		prom_len = len(prom_list[i])
+		if prom_len % audio_rvq_levels == 0 and False:
+			prom_list[i] = torch.Tensor(prom_list[i]).reshape( audio_rvq_levels, prom_len // audio_rvq_levels ).t()
+		else:
+			bins = [ [] for _ in range(audio_rvq_levels) ]
+			for pos in range( prom_len ):
+				rvq = pos % audio_rvq_levels
+				bins[rvq].append( prom_list[i][pos] )
+			nearest = ( len(bins) // audio_rvq_levels ) * audio_rvq_levels
+			bins = bins[:nearest]
+			prom_list[i] = torch.Tensor(bins).t().to(dtype=torch.int64)
+
+
+		resp_len = len(resp_list[i])
+		if len(resp_list[i]) % audio_rvq_levels == 0 and False:
+			resp_list[i] = torch.Tensor(resp_list[i]).reshape( audio_rvq_levels, resp_len // audio_rvq_levels ).t()
+		else:
+			bins = [ [] for _ in range(audio_rvq_levels) ]
+			for pos in range( resp_len ):
+				rvq = pos % audio_rvq_levels
+				bins[rvq].append( resp_list[i][pos] )
+			nearest = ( len(bins) // audio_rvq_levels ) * audio_rvq_levels
+			bins = bins[:nearest]
+			resp_list[i] = torch.Tensor(bins).t().to(dtype=torch.int64)
+		
+		text_list[i] = torch.Tensor( text_list[i] ).to(dtype=torch.int64)
+
+	return dict(
+		text_list=text_list,
+		prom_list=prom_list,
+		resp_list=resp_list
+	)
+
 # to-do: clean up this symmap mess
 def get_phone_symmap():
 	return cfg.tokenizer.get_vocab()
diff --git a/vall_e/engines/__init__.py b/vall_e/engines/__init__.py
index 40b806a..6890c62 100755
--- a/vall_e/engines/__init__.py
+++ b/vall_e/engines/__init__.py
@@ -33,7 +33,7 @@ def load_engines(training=True):
 		optimizer = None
 		lr_scheduler = None
 
-		inferencing = cfg.mode == "inferencing" or not model._cfg.training
+		inferencing = cfg.mode == "inferencing" or not model.hyper_config.training
 		backend = cfg.inference.backend if inferencing else cfg.trainer.backend
 		dtype = cfg.inference.dtype if inferencing else cfg.trainer.dtype
 		amp = cfg.inference.amp if inferencing else cfg.trainer.amp
@@ -43,7 +43,7 @@ def load_engines(training=True):
 		engine_class = _Engine if backend == "local" or inferencing else Engine
 
 		if inferencing:
-			model._cfg.training = False
+			model.hyper_config.training = False
 
 		if cfg.optimizations.replace and cfg.optimizations.linear:
 			model.model = ml.replace_linear( model.model )
@@ -83,7 +83,7 @@ def load_engines(training=True):
 			params.update(cfg.hyperparameters.optimizer_params)
 
 			optimizer = optimizer_class(
-				[ param for name, param in model.named_parameters() if name not in model._cfg.frozen_params ],
+				[ param for name, param in model.named_parameters() if name not in model.hyper_config.frozen_params ],
 				**params,
 			)
 
@@ -96,7 +96,7 @@ def load_engines(training=True):
 					raise ValueError(f'ScheduleFree not implemented with requested optimizer: {cfg.hyperparameters.optimizer}')
 
 				optimizer = scheduler_class(
-					[ param for name, param in model.named_parameters() if name not in model._cfg.frozen_params ],
+					[ param for name, param in model.named_parameters() if name not in model.hyper_config.frozen_params ],
 					lr = params['lr'],
 					warmup_steps = cfg.hyperparameters.warmup_steps
 				)
@@ -144,7 +144,7 @@ def load_engines(training=True):
 
 			model.load_state_dict(state, strict=cfg.trainer.strict_loading)
 
-		_cfg = model._cfg
+		hyper_config = model.hyper_config
 
 		# wrap if DDP is requested
 		if ddp:
@@ -161,7 +161,7 @@ def load_engines(training=True):
 			optimizer=optimizer,
 			lr_scheduler=lr_scheduler,
 
-			_cfg=_cfg,
+			hyper_config=hyper_config,
 			stats=stats
 		)
 		
diff --git a/vall_e/engines/base.py b/vall_e/engines/base.py
index ae20ad8..9369adc 100755
--- a/vall_e/engines/base.py
+++ b/vall_e/engines/base.py
@@ -52,9 +52,9 @@ if not distributed_initialized() and cfg.trainer.backend == "local": # and world
 # A very naive engine implementation using barebones PyTorch
 class Engine():
 	def __init__(self, *args, **kwargs):
-		if '_cfg' in kwargs:
-			self._cfg = kwargs['_cfg']
-			kwargs.pop("_cfg")
+		if 'hyper_config' in kwargs:
+			self.hyper_config = kwargs['hyper_config']
+			kwargs.pop("hyper_config")
 
 		self.module = kwargs['model'].to(cfg.device).to(torch.float32 if cfg.trainer.amp else cfg.trainer.dtype)
 		self.optimizer = kwargs['optimizer'] if 'optimizer' in kwargs else None
@@ -72,11 +72,11 @@ class Engine():
 
 	def freeze(self, freeze_all=True):
 		# set to freeze 
-		if self._cfg is None or not hasattr(self._cfg, "frozen_params"):
-			raise Exception("freeze_all=False yet self._cfg.frozen_params is None")
+		if self.hyper_config is None or not hasattr(self.hyper_config, "frozen_params"):
+			raise Exception("freeze_all=False yet self.hyper_config.frozen_params is None")
 
 		for name, param in self.module.named_parameters():
-			if (freeze_all and param.requires_grad) or (not freeze_all and name in self._cfg.frozen_params):
+			if (freeze_all and param.requires_grad) or (not freeze_all and name in self.hyper_config.frozen_params):
 				param.requires_grad_(False)
 				self._frozen_params.add(param)
 
@@ -87,9 +87,9 @@ class Engine():
 
 	@property
 	def _training(self):
-		if not hasattr(self, "_cfg"):
+		if not hasattr(self, "hyper_config"):
 			return True
-		return self._cfg.training
+		return self.hyper_config.training
 
 	@property
 	def global_step(self):
diff --git a/vall_e/engines/deepspeed.py b/vall_e/engines/deepspeed.py
index 1ef8333..08258ae 100755
--- a/vall_e/engines/deepspeed.py
+++ b/vall_e/engines/deepspeed.py
@@ -32,10 +32,10 @@ if not distributed_initialized() and cfg.trainer.backend == "deepspeed":
 
 class Engine(DeepSpeedEngine):
 	def __init__(self, *args, **kwargs):
-		self._cfg = None
-		if '_cfg' in kwargs:
-			self._cfg = kwargs['_cfg']
-			kwargs.pop("_cfg")
+		self.hyper_config = None
+		if 'hyper_config' in kwargs:
+			self.hyper_config = kwargs['hyper_config']
+			kwargs.pop("hyper_config")
 
 		kwargs['config'] = cfg.trainer.deepspeed.ds_cfg
 		kwargs['config_class'] = DeepSpeedConfig(kwargs['config'])
@@ -63,11 +63,11 @@ class Engine(DeepSpeedEngine):
 		self.max_nan_losses = 8
 
 	def freeze(self, freeze_all=True):
-		if self._cfg is None or not hasattr(self._cfg, "frozen_params"):
-			raise Exception("freeze_all=False yet self._cfg.frozen_params is None")
+		if self.hyper_config is None or not hasattr(self.hyper_config, "frozen_params"):
+			raise Exception("freeze_all=False yet self.hyper_config.frozen_params is None")
 
 		for name, param in self.module.named_parameters():
-			if (freeze_all and param.requires_grad) or (not freeze_all and name in self._cfg.frozen_params):
+			if (freeze_all and param.requires_grad) or (not freeze_all and name in self.hyper_config.frozen_params):
 				param.requires_grad_(False)
 				self._frozen_params.add(param)
 
@@ -78,7 +78,7 @@ class Engine(DeepSpeedEngine):
 	
 	@property
 	def _training(self):
-		return self._cfg.training
+		return self.hyper_config.training
 
 	@property
 	def global_step(self):
diff --git a/vall_e/models/__init__.py b/vall_e/models/__init__.py
index 59a86d7..97309ae 100755
--- a/vall_e/models/__init__.py
+++ b/vall_e/models/__init__.py
@@ -1,23 +1,34 @@
 from .ar_nar import AR_NAR
+from .experimental import Model as Experimental
 
 def get_model(cfg, training=True):
 	name = cfg.name
 
-	model = AR_NAR(
-		n_tokens=cfg.tokens,
-		d_model=cfg.dim,
-		n_heads=cfg.heads,
-		n_layers=cfg.layers,
-		n_experts=cfg.experts,
-		
-		p_dropout=cfg.dropout,
-		
-		l_padding = cfg.input_alignment,
-		
-		training = training,
-		config = cfg,
-	)
-	model._cfg = cfg
+	if not cfg.experimental:
+		model = AR_NAR(
+			n_tokens=cfg.tokens,
+			d_model=cfg.dim,
+			n_heads=cfg.heads,
+			n_layers=cfg.layers,
+			n_experts=cfg.experts,
+			
+			p_dropout=cfg.dropout,
+			
+			l_padding = cfg.input_alignment,
+			
+			training = training,
+			config = cfg,
+		)
+		model._cfg = cfg
+	else:
+		model = Experimental(
+			d_model=cfg.dim,
+			n_layers=cfg.layers,
+			n_heads=cfg.heads,
+			p_dropout=cfg.dropout,
+
+			config = cfg,
+		)
 
 	print(f"{name} ({next(model.parameters()).dtype}): {sum(p.numel() for p in model.parameters() if p.requires_grad)} parameters")
 
diff --git a/vall_e/models/base.py b/vall_e/models/base.py
index 6a86ca3..f1dd72a 100755
--- a/vall_e/models/base.py
+++ b/vall_e/models/base.py
@@ -64,7 +64,7 @@ try:
 	def BitNetTransformerBlock_forward(self, x: Tensor, *args, **kwargs) -> Tensor:
 		skip = x
 		for attn, ffn in zip(self.layers, self.ffn_layers):
-			if x.requires_grad and self.activation_checkpointing:
+			if x.requires_grad and self.gradient_checkpointing:
 				x, _ = checkpoint(attn, x, x, x, is_causal=True, *args, **kwargs, use_reentrant=False)
 			else:
 				x, _ = attn(x, x, x, is_causal=True, *args, **kwargs)
@@ -83,13 +83,13 @@ try:
 			num_tokens: int,
 			heads=8,
 			ff_mult=4,
-			activation_checkpointing = True
+			gradient_checkpointing = True
 		):
 			super().__init__()
 
 			self.transformer = BitNetTransformerBlock( dim=dim, depth=depth, heads=heads, ff_mult=ff_mult )
 			self.norm = BitNetRMSNorm(dim)
-			self.transformer.activation_checkpointing = activation_checkpointing
+			self.transformer.gradient_checkpointing = gradient_checkpointing
 
 		def forward(self, x):
 			x = self.transformer(x)
@@ -431,9 +431,9 @@ class Base(nn.Module):
 		return -100
 
 	def loss_factor(self, k):
-		if self.config is None:
+		if self.hyper_config is None:
 			return 1.0
-		return self.config.loss_factors[k] if k in self.config.loss_factors else 1.0
+		return self.hyper_config.loss_factors[k] if k in self.hyper_config.loss_factors else 1.0
 
 	def __init__(
 		self,
@@ -452,8 +452,8 @@ class Base(nn.Module):
 	):
 		super().__init__()
 		self.training = training
-		self.config = config
-		self.activation_checkpointing = self.config.activation_checkpointing if self.config is not None else True
+		self.hyper_config = config
+		self.gradient_checkpointing = self.hyper_config.gradient_checkpointing if self.hyper_config is not None else True
 
 		self.n_tokens = n_tokens
 		self.d_model = d_model
@@ -482,13 +482,13 @@ class Base(nn.Module):
 			self.proms_emb = AudioEmbedding(
 				[n_prom_tokens] * self.n_prom_levels, d_model,
 				levels=self.n_prom_levels if self.version > 3 else None,
-				sums=self.config.audio_embedding_sums if self.config is not None else True,
+				sums=self.hyper_config.audio_embedding_sums if self.hyper_config is not None else True,
 			)
 			# [1025] + [1024] * 8
 			self.resps_emb = AudioEmbedding(
 				[n_resp_tokens] + [n_resp_tokens - 1] * (self.n_resp_levels - 1), d_model,
 				levels=self.n_resp_levels if self.version > 3 else None,
-				sums=self.config.audio_embedding_sums if self.config is not None else True
+				sums=self.hyper_config.audio_embedding_sums if self.hyper_config is not None else True
 			)
 
 		
@@ -502,20 +502,20 @@ class Base(nn.Module):
 		self.sep = nn.Parameter(torch.randn(d_model))
 
 		# ick, there has to be a better way
-		hf_attention = self.config.attention if self.config is not None else None
+		hf_attention = self.hyper_config.attention if self.hyper_config is not None else None
 
-		if self.config.attention == "auto":
+		if self.hyper_config.attention == "auto":
 			if "flash" in AVAILABLE_ATTENTIONS:
-				self.config.attention = "flash"
+				self.hyper_config.attention = "flash"
 			elif "xformers" in AVAILABLE_ATTENTIONS:
-				self.config.attention = "xformers"
+				self.hyper_config.attention = "xformers"
 			else:
-				self.config.attention = "mem_efficient"
+				self.hyper_config.attention = "mem_efficient"
 
-		if self.config.attention in ["xformers", "mem_efficient", "math", "flash"]:
+		if self.hyper_config.attention in ["xformers", "mem_efficient", "math", "flash"]:
 			hf_attention = None
-			if self.config.attention not in AVAILABLE_ATTENTIONS:
-				raise ValueError(f"Requesting attention `{self.config.attention}` but is not available. Currently available: {AVAILABLE_ATTENTIONS}")
+			if self.hyper_config.attention not in AVAILABLE_ATTENTIONS:
+				raise ValueError(f"Requesting attention `{self.hyper_config.attention}` but is not available. Currently available: {AVAILABLE_ATTENTIONS}")
 
 
 		if self.arch_type == "transformer":
@@ -538,12 +538,12 @@ class Base(nn.Module):
 					num_hidden_layers=n_layers,
 					num_attention_heads=n_heads,
 					attention_dropout=p_dropout if training else 0.0,
-					num_key_value_heads=self.config.kv_heads if self.config.kv_heads > 0 else n_heads,
+					num_key_value_heads=self.hyper_config.kv_heads if self.hyper_config.kv_heads > 0 else n_heads,
 					hidden_act="gelu",
 					is_encoder_decoder=False,
 					is_decoder=True,
 					attn_implementation=hf_attention,
-					#gradient_checkpointing=self.activation_checkpointing,
+					#gradient_checkpointing=self.gradient_checkpointing,
 				))
 			else:
 				self.model = MixtralModel(MixtralConfig(
@@ -554,7 +554,7 @@ class Base(nn.Module):
 					num_hidden_layers=n_layers,
 					num_attention_heads=n_heads,
 					attention_dropout=p_dropout if training else 0.0,
-					num_key_value_heads=self.config.kv_heads if self.config.kv_heads > 0 else n_heads,
+					num_key_value_heads=self.hyper_config.kv_heads if self.hyper_config.kv_heads > 0 else n_heads,
 					sliding_window=75 * 12, # 12 second context window
 					output_router_logits=training,
 					hidden_act="gelu",
@@ -563,10 +563,10 @@ class Base(nn.Module):
 					num_local_experts=n_experts,
 					num_experts_per_tok=min(2, n_experts),
 					attn_implementation=hf_attention,
-					#gradient_checkpointing=self.activation_checkpointing,
+					#gradient_checkpointing=self.gradient_checkpointing,
 				))
 
-			if self.activation_checkpointing and not self.model.gradient_checkpointing:
+			if self.gradient_checkpointing and not self.model.gradient_checkpointing:
 				self.model.gradient_checkpointing_enable(gradient_checkpointing_kwargs=dict(
 					use_reentrant=False
 				))
@@ -589,7 +589,7 @@ class Base(nn.Module):
 					is_encoder_decoder=False,
 					is_decoder=True,
 					attn_implementation=hf_attention,
-					#gradient_checkpointing=self.activation_checkpointing,
+					#gradient_checkpointing=self.gradient_checkpointing,
 				))
 			else:
 				self.model = MixtralModel(MixtralConfig(
@@ -609,10 +609,10 @@ class Base(nn.Module):
 					num_local_experts=n_experts,
 					num_experts_per_tok=min(2, n_experts),
 					attn_implementation=hf_attention,
-					#gradient_checkpointing=self.activation_checkpointing,
+					#gradient_checkpointing=self.gradient_checkpointing,
 				))
 
-			if self.activation_checkpointing and not self.model.gradient_checkpointing:
+			if self.gradient_checkpointing and not self.model.gradient_checkpointing:
 				self.model.gradient_checkpointing_enable(gradient_checkpointing_kwargs=dict(
 					use_reentrant=False
 				))
@@ -628,7 +628,7 @@ class Base(nn.Module):
 				decoder_ffn_embed_dim=d_model * 4,
 				decoder_layers=n_layers,
 				dropout=p_dropout if training else 0.0,
-				checkpoint_activations=self.activation_checkpointing,
+				checkpoint_activations=self.gradient_checkpointing,
 				activation_fn="gelu",
 				use_layernorm=self.version < 3,
 				use_biases=self.version < 3,
@@ -660,7 +660,7 @@ class Base(nn.Module):
 				decoder_ffn_embed_dim=d_model * 4,
 				decoder_layers=n_layers,
 				dropout=p_dropout if training else 0.0,
-				checkpoint_activations=self.activation_checkpointing,
+				checkpoint_activations=self.gradient_checkpointing,
 				activation_fn="gelu",
 				use_glu=False, # self.version >= 3,
 
@@ -673,7 +673,7 @@ class Base(nn.Module):
 
 			self.model = RetNetDecoder_HF(RetNetConfig_HF(**kwargs))
 
-			if self.activation_checkpointing and not self.model.gradient_checkpointing:
+			if self.gradient_checkpointing and not self.model.gradient_checkpointing:
 				self.model.gradient_checkpointing_enable(gradient_checkpointing_kwargs=dict(
 					use_reentrant=False
 				))
@@ -684,13 +684,13 @@ class Base(nn.Module):
 				depth=n_layers,
 				heads=n_heads,
 				ff_mult=4,
-				activation_checkpointing=self.activation_checkpointing,
+				gradient_checkpointing=self.gradient_checkpointing,
 			)
 		else:
 			raise RuntimeError(f'Unknown arch specified: {self.arch_type}')
 
-		if self.config.attention in ["xformers", "auto", "mem_efficient", "math", "flash"]:
-			self.model = ml.replace_attention( self.model, klass=Llama_Attention, target=LlamaAttention, mode=self.config.attention )
+		if self.hyper_config.attention in ["xformers", "auto", "mem_efficient", "math", "flash"]:
+			self.model = ml.replace_attention( self.model, klass=Llama_Attention, target=LlamaAttention, mode=self.hyper_config.attention )
 
 		self.classifier = nn.Linear(d_model, n_resp_tokens)
 
@@ -877,7 +877,7 @@ class Base(nn.Module):
 		quant_levels: Tensor | None = None,
 	):
 		# old, "naive" way, no loss factoring
-		if not self.config.loss_factors:
+		if not self.hyper_config.loss_factors:
 			target_list = []
 			for batch in inputs:
 				target = []
diff --git a/vall_e/models/experimental.py b/vall_e/models/experimental.py
index 606a839..2875ed0 100644
--- a/vall_e/models/experimental.py
+++ b/vall_e/models/experimental.py
@@ -1,9 +1,20 @@
+"""
+This is an experiment to:
+* entertain a thought to try and abide by HF's transformers API (to benefit from caching better)
+* conform to a single embedding (instead of a bunch of them) by folding/unfolding inputs
+* stop trying to make a mixed AR+NAR model work since it seems lobotomized if I keep trying to enforce both recurrent and parallel inferencing (despite a penalty cost)
+	+ I will not cave and go with codebook patterns, not yet.
+"""
+
 from ..config import cfg
 
+from ..data import fold_inputs, unfold_outputs
+
 import torch
 from torch.nn.utils.rnn import pad_sequence
 from torch import Tensor
 from torch.nn import CrossEntropyLoss
+from torch.utils.checkpoint import checkpoint
 
 import random
 import math
@@ -21,144 +32,40 @@ except Exception as e:
 	pass
 
 try:
-	from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel, MambaConfig
+	from mamba_ssm.models.mixer_seq_simple import MambaLMHeadModel, MambaConfig, MixerModel as MambaMixelModel, layer_norm_fn as MambaLayerNormFn, RMSNorm as MambaRMSNorm
+
+	def MambaMixelModel_forward(self, input_ids, inference_params=None, **mixer_kwargs):
+		hidden_states = self.embedding(input_ids)
+		residual = None
+		for layer in self.layers:
+			if self.gradient_checkpointing and hidden_states.requires_grad:
+				hidden_states, residual = checkpoint( layer, hidden_states, residual, inference_params=inference_params, use_reentrant=False )
+			else:
+				hidden_states, residual = layer( hidden_states, residual, inference_params=inference_params )
+		if not self.fused_add_norm:
+			residual = (hidden_states + residual) if residual is not None else hidden_states
+			hidden_states = self.norm_f(residual.to(dtype=self.norm_f.weight.dtype))
+		else:
+			# Set prenorm=False here since we don't need the residual
+			hidden_states = MambaLayerNormFn(
+				hidden_states,
+				self.norm_f.weight,
+				self.norm_f.bias,
+				eps=self.norm_f.eps,
+				residual=residual,
+				prenorm=False,
+				residual_in_fp32=self.residual_in_fp32,
+				is_rms_norm=isinstance(self.norm_f, MambaRMSNorm)
+			)
+		return hidden_states
+
+	MambaMixelModel.forward = MambaMixelModel_forward
+
 	AVAILABLE_ARCHES.append("mamba")
 except Exception as e:
 	print("Error importing `mamba` arch:", e)
 	pass
 
-def _create_mask(l, device):
-	seq = torch.arange(max(l), device=device).unsqueeze(0)  # (1 t)
-	stop = torch.tensor(l, device=device).unsqueeze(1)  # (b 1)
-	return (seq < stop).float()  # (b t)
-
-def list_to_tensor(x_list: list[Tensor]):
-	l = list(map(len, x_list))
-	x = pad_sequence(x_list).t()
-
-	m = _create_mask(l, x_list[0].device)
-	m = m.to(x)
-	return x, m
-
-# fold into a typical LLM sequence (one embedding rather than split embeddings)
-def fold(
-	text_list = [],
-	proms_list = [],
-	resp_list = [],
-
-	ignore_index = None,
-
-	sep = 3,
-	stop = 3,
-	
-	text_tokens = 256,
-	audio_tokens = 1024,
-	audio_rvq_levels = cfg.model.prom_levels
-):
-
-	device = text_list[0].device
-	batch_size = len(text_list)
-	input_ids = [ [] for _ in range(batch_size) ]
-
-	offset = 0
-	
-	sep = torch.Tensor([ sep ])
-	stop = torch.Tensor([ stop ])
-
-	for i, text in enumerate(text_list):
-		seq = text.to("cpu", dtype=torch.int64)
-		input_ids[i].append( seq )
-		input_ids[i].append( sep )
-	
-	offset = text_tokens
-	for i, prom in enumerate(proms_list):
-		if ignore_index is not None:
-			seq = torch.Tensor( [ ignore_index for _ in range( prom.shape[0] * prom.shape[1] ) ] ).to("cpu", dtype=torch.int64)
-		else:
-			seq = prom.flatten().to("cpu", dtype=torch.int64)
-			for idx, token in enumerate( seq ):
-				token += offset + ( audio_tokens * ( idx % audio_rvq_levels ) )
-
-		input_ids[i].append( seq )
-		input_ids[i].append( sep )
-	
-	offset = text_tokens + (audio_tokens * audio_rvq_levels)
-	for i, resp in enumerate(resp_list):
-		seq = resp.flatten().to("cpu", dtype=torch.int64)
-		for idx, token in enumerate( seq ):
-			token += offset + ( audio_tokens * ( idx % audio_rvq_levels ) )
-		input_ids[i].append( seq )
-		input_ids[i].append( stop )
-
-	for i, batch in enumerate(input_ids):
-		input_ids[i] = torch.concat(input_ids[i], dim=-1).to(device=device, dtype=torch.int64)
-
-	return list_to_tensor(input_ids)
-
-# unfold from one unified token ID space to separate token spaces
-def unfold(
-	input_ids,
-
-	sep = 3,
-	stop = 3,
-	
-	text_tokens = 256,
-	audio_tokens = 1024,
-	audio_rvq_levels = cfg.model.prom_levels
-):
-	device = input_ids.device
-	batch_size = input_ids.shape[0]
-
-	text_list = [ [] for _ in range(batch_size) ]
-	prom_list = [ [] for _ in range(batch_size) ]
-	resp_list = [ [] for _ in range(batch_size) ]
-
-	for i, batch in enumerate( input_ids ):
-		for idx, token in enumerate( batch ):
-			id = token.item()
-			if id == sep or id == stop:
-				continue
-
-			if 0 <= id and id < text_tokens:
-				text_list[i].append( id )
-			elif text_tokens <= id and id < text_tokens + (audio_tokens * audio_rvq_levels):
-				prom_list[i].append( (id - text_tokens) % audio_tokens )
-			elif text_tokens + (audio_tokens * audio_rvq_levels) <= id:
-				resp_list[i].append( (id - text_tokens) % audio_tokens )
-
-		prom_len = len(prom_list[i])
-		if prom_len % audio_rvq_levels == 0 and False:
-			prom_list[i] = torch.Tensor(prom_list[i]).reshape( audio_rvq_levels, prom_len // audio_rvq_levels ).t()
-		else:
-			bins = [ [] for _ in range(audio_rvq_levels) ]
-			for pos in range( prom_len ):
-				rvq = pos % audio_rvq_levels
-				bins[rvq].append( prom_list[i][pos] )
-			nearest = ( len(bins) // audio_rvq_levels ) * audio_rvq_levels
-			bins = bins[:nearest]
-			prom_list[i] = torch.Tensor(bins).t().to(dtype=torch.int64)
-
-
-		resp_len = len(resp_list[i])
-		if len(resp_list[i]) % audio_rvq_levels == 0 and False:
-			resp_list[i] = torch.Tensor(resp_list[i]).reshape( audio_rvq_levels, resp_len // audio_rvq_levels ).t()
-		else:
-			bins = [ [] for _ in range(audio_rvq_levels) ]
-			for pos in range( resp_len ):
-				rvq = pos % audio_rvq_levels
-				bins[rvq].append( resp_list[i][pos] )
-			nearest = ( len(bins) // audio_rvq_levels ) * audio_rvq_levels
-			bins = bins[:nearest]
-			resp_list[i] = torch.Tensor(bins).t().to(dtype=torch.int64)
-		
-		text_list[i] = torch.Tensor( text_list[i] ).to(dtype=torch.int64)
-
-	return dict(
-		text_list=text_list,
-		prom_list=prom_list,
-		resp_list=resp_list
-	)
-
 
 SELECTED_ARCH = cfg.model.arch_type 
 if SELECTED_ARCH not in AVAILABLE_ARCHES:
@@ -179,9 +86,12 @@ class Model(LlmArchClass):
 		n_heads=16,
 		p_dropout=0.1,
 
-		attention_backend=None,
-		activation_checkpointing=True,
+		config = None,
 	):
+		self.hyper_config  = config
+		
+		hf_attention = config.attention if config is not None else None
+		gradient_checkpointing = config.gradient_checkpointing if config is not None else True
 
 		if SELECTED_ARCH == "llama":
 			super().__init__(config=LlamaConfig(
@@ -197,10 +107,10 @@ class Model(LlmArchClass):
 				hidden_act="gelu",
 				is_encoder_decoder=False,
 				is_decoder=True,
-				attn_implementation=attention_backend,
+				attn_implementation=hf_attention,
 			))
 			
-			if activation_checkpointing:
+			if gradient_checkpointing:
 				self.gradient_checkpointing_enable(gradient_checkpointing_kwargs=dict(
 					use_reentrant=False
 				))
@@ -209,9 +119,11 @@ class Model(LlmArchClass):
 				vocab_size=256 + (1024 * cfg.model.prom_levels) + (1024 * cfg.model.prom_levels) + 1,
 				d_model=d_model,
 				n_layer=n_layers*2,
-				#ssm_cfg={"layer": "Mamba2"},
+				#ssm_cfg={"layer": "Mamba2"}, # will ALWAYS nan
 			))
 
+			self.backbone.gradient_checkpointing = gradient_checkpointing
+
 
 	def forward(
 		self,
@@ -293,9 +205,9 @@ def example_usage():
 	proms_list = proms_list[:1]
 	resps_list = resps_list[:1]
 
-	input_ids, attention_mask = fold(text_list, proms_list, resps_list)
-	target_ids, target_attention_mask = fold(text_list, proms_list, resps_list, ignore_index=-100)
-	prefix_input_ids, prefix_attention_mask = fold(text_list, proms_list)
+	input_ids, attention_mask = fold_inputs(text_list, proms_list, resps_list)
+	target_ids, target_attention_mask = fold_inputs(text_list, proms_list, resps_list, ignore_index=-100)
+	prefix_input_ids, prefix_attention_mask = fold_inputs(text_list, proms_list)
 
 	kwargs = {}
 	model = Model(**kwargs).to(device)
@@ -373,7 +285,7 @@ def example_usage():
 		else:
 			output = model.generate(input_ids=prefix_input_ids, attention_mask=prefix_attention_mask, max_length=steps, eos_token_id=3, do_sample=False)
 
-		unfolded = unfold( output )
+		unfolded = unfold_outputs( output )
 		for i, batch in enumerate(unfolded["resp_list"]):
 			_ = decode_to_file(batch.to(device=device), f"data/{SELECTED_ARCH}.{cfg.audio_backend}.{i}.{name}.wav", device=device)
 
diff --git a/vall_e/models/transformer.py b/vall_e/models/transformer.py
index 4d749c1..a2093f4 100755
--- a/vall_e/models/transformer.py
+++ b/vall_e/models/transformer.py
@@ -15,7 +15,29 @@ from torch import Tensor, einsum, nn
 from torch.utils.checkpoint import checkpoint
 
 from ..utils import wrapper as ml
-from .adaln import AdaLN
+
+class AdaLN(nn.Module):
+	def __init__(self, d_model, n_levels, eps=1e-5, k=0.1, c=2):
+		super().__init__()
+		self.eps = eps
+		self.emb = nn.Embedding(n_levels, d_model * 2)
+		self.k = k
+		self.c = c
+		nn.init.zeros_(self.emb.weight)
+
+	def forward(self, x, l):
+		h = F.layer_norm(x, x.shape[-1:], eps=self.eps)
+
+		# The initial implementation (https://github.com/enhuiz/vall-e/blob/fbf023448c08e55c0422eefed7fc234cf8b76680/vall_e/vall_e/base.py#L135)
+		# performed worse than vanilla LayerNorm.
+		# The authors mentioned another AdaNorm paper (https://openreview.net/pdf?id=HyxndNrxLB) as they introduce AdaLN.
+		# Did they use AdaNorm inside AdaLN? (as follows)
+		h = self.c * (1 - (self.k * h).detach()) * h
+
+		logγ, β = self.emb(l).unsqueeze(1).chunk(2, dim=-1)
+		y = logγ.exp() * h + β
+
+		return y
 
 class SinusoidalEmbedding(nn.Module):
 	def __init__(self, d_model):
diff --git a/vall_e/train.py b/vall_e/train.py
index a9339e8..0dec17c 100755
--- a/vall_e/train.py
+++ b/vall_e/train.py
@@ -5,6 +5,7 @@ from .data import create_train_val_dataloader
 from .emb import qnt
 
 from .utils import setup_logging, to_device, trainer, flatten_dict, do_gc
+from .data import fold_inputs, unfold_outputs
 
 import auraloss
 import json
@@ -25,12 +26,29 @@ mel_stft_loss = auraloss.freq.MelSTFTLoss(cfg.sample_rate, device="cpu")
 
 def train_feeder(engine, batch):
 	with torch.autocast("cuda", dtype=cfg.trainer.dtype, enabled=cfg.trainer.amp):
-		engine(
-			text_list=batch["text"],
-			proms_list=[prom[:, :engine._cfg.prom_levels] for prom in batch["proms"]], # reduce the input prompt to the target prom level
-			resps_list=batch["resps"],
-			lang_list=batch["lang"],
-		)
+		if engine.hyper_config.experimental:
+			input_ids, attention_mask = fold_inputs(
+				text_list=batch["text"],
+				prom_list=batch["proms"],
+				resp_list=batch["resps"],
+			)
+			target_ids, target_attention_mask = fold_inputs(
+				text_list=batch["text"],
+				prom_list=batch["proms"],
+				resp_list=batch["resps"],
+				ignore_index=-100
+			)
+			engine(
+				input_ids=input_ids,
+				labels=target_ids
+			)
+		else:
+			engine(
+				text_list=batch["text"],
+				proms_list=[prom[:, :engine._cfg.prom_levels] for prom in batch["proms"]], # reduce the input prompt to the target prom level
+				resps_list=batch["resps"],
+				lang_list=batch["lang"],
+			)
 
 		losses = engine.gather_attribute("loss")
 		stat = engine.gather_attribute("stats")
@@ -48,22 +66,6 @@ def train_feeder(engine, batch):
 
 @torch.inference_mode()
 def run_eval(engines, eval_name, dl):
-	AR = None
-	NAR = None
-	AR_NAR = None
-
-	names = []
-	for name, engine in engines.items():
-		if name[:6] == "ar+nar":
-			AR_NAR = engine
-		elif name[:2] == "ar":
-			AR = engine
-		elif name[:3] == "nar":
-			NAR = engine
-		else:
-			continue
-		names.append(name)
-
 	stats = defaultdict(list)
 	stats['loss'] = []
 
@@ -101,44 +103,22 @@ def run_eval(engines, eval_name, dl):
 		batch: dict = to_device(next(iter(dl)), cfg.device)
 		processed += len(batch["text"])
 
-		# if we're training both models, provide output for both
-		if AR is not None and NAR is not None:
-			name = "+".join(names)
+		for name in engines:
+			engine = engines[name]
 
-			resps_list = AR(text_list=batch["text"], proms_list=batch["proms"], lang_list=batch["lang"], max_steps=cfg.evaluation.steps, sampling_temperature=cfg.evaluation.ar_temperature)
-			resps_list = [ r.unsqueeze(-1) for r in resps_list ]
-			resps_list = NAR(text_list=batch["text"], proms_list=batch["proms"], lang_list=batch["lang"], resps_list=resps_list, sampling_temperature=cfg.evaluation.nar_temperature)
+			if engine.hyper_config.experimental:
+				input_ids, attention_mask = fold_inputs(
+					text_list=batch["text"],
+					proms_list=batch["proms"],
+				)
+				output = engine.model.generate(input_ids=input_ids, attention_mask=attention_mask, max_length=cfg.evaluation.steps, eos_token_id=3, do_sample=False)
+				resps_list = unfold_outputs( output )["resp_list"]
+			else:
+				resps_list = engine(text_list=batch["text"], proms_list=batch["proms"], lang_list=batch["lang"], max_steps=cfg.evaluation.steps, sampling_temperature=cfg.evaluation.ar_temperature)
+				resps_list = [ r.unsqueeze(-1) for r in resps_list ]
+				resps_list = engine(text_list=batch["text"], proms_list=batch["proms"], lang_list=batch["lang"], resps_list=resps_list, sampling_temperature=cfg.evaluation.nar_temperature)
 
 			process( name, batch, resps_list )
-		else:
-			for name in engines:
-				model = engines[name]
-
-				if name.startswith("ar+nar"):
-					resps_list = AR_NAR(text_list=batch["text"], proms_list=batch["proms"], lang_list=batch["lang"], max_steps=cfg.evaluation.steps, sampling_temperature=cfg.evaluation.ar_temperature)
-					resps_list = [ r.unsqueeze(-1) for r in resps_list ]
-					resps_list = AR_NAR(text_list=batch["text"], proms_list=batch["proms"], lang_list=batch["lang"], resps_list=resps_list, sampling_temperature=cfg.evaluation.nar_temperature)
-				elif name.startswith("ar"):
-					resps_list = model(
-						text_list=batch["text"],
-						proms_list=batch["proms"],
-						lang_list=batch["lang"],
-						max_steps=cfg.evaluation.steps,
-						sampling_temperature=cfg.evaluation.ar_temperature,
-					)
-					resps_list = [r.unsqueeze(-1) for r in resps_list]
-				elif name.startswith("nar"):
-					resps_list = model(
-						text_list=batch["text"],
-						proms_list=batch["proms"],
-						lang_list=batch["lang"],
-						resps_list=[r[..., 0].unsqueeze(-1) for r in batch["resps"]],
-						sampling_temperature=cfg.evaluation.nar_temperature,
-					)
-				else:
-					raise NotImplementedError(name)
-
-				process( name, batch, resps_list )
 
 
 	stats = {k: sum(v) / len(v) for k, v in stats.items()}