I am using a Lexicon MPX1 rack effects unit in the Loop of my Mesa 550. Here's my question: I have been playing around with the input and output volumes on the rack unit and currently I have the Volume up on the Amp, and have been lowering the output volume on the Rack unit. I am doing any harm to the Amp (Tubes and or Transformers) I feel like I have the preamp tubes running Hot and the Output tubes aren't seeing the same level. I am able to get ok tones this way at very very low volume (quieter than "Bedroom level"). Thanks in advance.