@ toddalin thanks so much for bringing the topic up of tube amplifiers. Your design/ piece of equipment looks pretty intense. For everyone else there is a guy out of England that made me a loaded switcher box because I have a tube amp as well as a set of hybrid mono-blocks that I felt needed the extra protection and I didn't want to fiddlle-faddle around with switching cables around. I think the idea of comparison comes down to your ears and what sounds "right" for you. You can do all sorts of tests such as have been mentioned but in the end it has to "sound right" for you, your ears.
How do you A/B amps in your system?
Comparing two different amps in my system of separates requires changing speaker cable connections, inputs, and sometimes system volume. Do you have any tricks you use to simplicity the switch over and minimize time between hearing one then the other? I know audio reviewers make comparisons between amps, but for me there is more subjectivity at play than say comparing two input components. Is this just the nature of the beast, or do you veteran listeners have tips and tricks!?