diff --git a/vall_e/engines/__init__.py b/vall_e/engines/__init__.py
index 5056bda..7b30418 100755
--- a/vall_e/engines/__init__.py
+++ b/vall_e/engines/__init__.py
@@ -148,8 +148,9 @@ def load_engines(training=True, **model_kwargs):
 			else:
 				raise ValueError(f'Optimizer specified not implemented: {cfg.hyperparameters.optimizer}')
 
-			muon_params = cfg.hyperparameters.optimizer_params.pop("muon", None)
-			params.update(cfg.hyperparameters.optimizer_params)
+			if cfg.hyperparameters.optimizer_params is not None:
+				muon_params = cfg.hyperparameters.optimizer_params.pop("muon", None)
+				params.update(cfg.hyperparameters.optimizer_params)
 
 			if muon_params is not None:
 				muon_params["params"] = [ param for name, param in model.model.named_parameters() if param.ndim >= 2 and f'model.{name}' not in model.config.frozen_params ]
diff --git a/vall_e/models/ar_nar.py b/vall_e/models/ar_nar.py
index 0db8af5..9d6f76e 100644
--- a/vall_e/models/ar_nar.py
+++ b/vall_e/models/ar_nar.py
@@ -1428,7 +1428,7 @@ def example_usage():
 		available_tasks = ["tts-nar"]
 
 	model = AR_NAR(**kwargs).to(cfg.device)
-	steps = 100 // batch_size
+	steps = 250 // batch_size
 
 	optimizer = cfg.hyperparameters.optimizer.lower() if cfg.yaml_path is not None else "prodigy"
 	scheduler = cfg.hyperparameters.scheduler.lower() if cfg.yaml_path is not None else ""
@@ -1473,7 +1473,7 @@ def example_usage():
 
 	_logger.info(f"Optimizer: {optimizer}\tLearning rate: {learning_rate}")
 	
-	muon_params = cfg.hyperparameters.optimizer_params.pop("muon", None)
+	muon_params = cfg.hyperparameters.optimizer_params.pop("muon", None) if cfg.hyperparameters.optimizer_params is not None else None
 	if muon_params is not None:
 		muon_params["params"] = [ param for name, param in model.model.named_parameters() if param.ndim >= 2 ]
 		adam_params = [ param for name, param in model.model.named_parameters() if param.ndim < 2 ] + [ param for name, param in model.named_parameters() if not name.startswith('model.') ]
diff --git a/vall_e/models/base.py b/vall_e/models/base.py
index aa1a5ba..c4ec0c5 100755
--- a/vall_e/models/base.py
+++ b/vall_e/models/base.py
@@ -547,6 +547,7 @@ class Base(nn.Module):
 		self.gradient_checkpointing = self.config.gradient_checkpointing if self.config is not None else True
 
 		self.stop_token = self.n_audio_tokens # id 1024
+		self.mask_token = self.n_audio_tokens + 1 # id 1024
 		self.causal = "ar" in self.capabilities or "len" in self.capabilities
 		self.version = self.config.version if self.config is not None else 5
 		self.causal_size = self.config.experimental.causal_size if self.config is not None else (1 if self.causal else 0)
@@ -715,7 +716,7 @@ class Base(nn.Module):
 		if self.version >= 7:
 			if monolithic_audio_encoder:
 				self.audio_emb = AudioEncoder(
-					n_tokens=n_audio_tokens + 1, # masked token
+					n_tokens=n_audio_tokens + 2, # stop + masked token
 					n_levels=self.n_resp_levels,
 					token_dim=d_model,
 				)
@@ -726,7 +727,7 @@ class Base(nn.Module):
 					token_dim=d_model,
 				)
 				self.resps_emb = AudioEncoder(
-					n_tokens=n_audio_tokens + 1, # masked token
+					n_tokens=n_audio_tokens + 2, # stop + masked token
 					n_levels=self.n_resp_levels,
 					token_dim=d_model,
 				)
@@ -1310,9 +1311,9 @@ class Base(nn.Module):
 				elif name == "resp":
 					if self.version >= 7:
 						if self.audio_emb is not None:
-							embedding = self.audio_emb( input, dropout_mask=dropout_mask, dropout_token=self.stop_token )
+							embedding = self.audio_emb( input, dropout_mask=dropout_mask, dropout_token=self.mask_token )
 						else:
-							embedding = self.resps_emb( input, dropout_mask=dropout_mask, dropout_token=self.stop_token )
+							embedding = self.resps_emb( input, dropout_mask=dropout_mask, dropout_token=self.mask_token )
 					# if training NAR-len RVQ level 0
 					elif dropout_mask is not None:
 						embedding = self.resps_emb(
diff --git a/vall_e/utils/ml.py b/vall_e/utils/ml.py
index a84045c..fa4502f 100755
--- a/vall_e/utils/ml.py
+++ b/vall_e/utils/ml.py
@@ -132,9 +132,8 @@ except Exception as e:
 try:
 	from muon import Muon as Muon
 except Exception as e:
-	raise e
-	#_logger.warning(f'Error while importing Muon: {str(e)}')
-	#pass
+	_logger.warning(f'Error while importing Muon: {str(e)}')
+	pass
 
 # https://github.com/konstmish/prodigy
 try: