How do you A/B amps in your system?

Thanks for the thoughts, and @lanx0003 thanks for the exact tool. Of course on Audiogon we will have to debate the sound of the switcher! Lol

It dawns on me that the advice to listen long also allows for the amp to settle into the system (which seems like voodoo but I always notice that it helps).

Thanks @carlsbad2 . I do that in my studio, sometimes, but it's not an option in our living room 😄

Thank you all for sharing your experiences and what you have found useful. @toddalin thanks for sharing your design and the warning about tube amps (which is one of what I'm comparing). And I guess @zlone your experience shows that it's possible to hear well enough to overcome bias, which was one of my primary questions.

Thanks, @mashif, I also have a Schiit Freya preamp available -- which has multiple pre-out options. It would help with allowing keeping input connections into different amps and remove one element from switching, requiring just the speaker cable changes.👍🏻

It makes total sense that you gain one set of information from long-term varied listening and another from the immediate A/B of a section that the switching devices provides. The one is more of a gestalt of the amp while the other provides details that might be lost in a fog of memory. Thanks again everyone for this informative discussion, and for keeping our tube amps from burning up should we try out a switcher! 

@bassbuyer That looks like a cool one. I love that the VU meters are so broken down in the sub 10 Watts area. You can watch to see how often you get beyond the first watt!

@webking185 You make such a nice point: Once you are listening to a certain level of sound quality, you're not so much listening for a difference between apples and oranges as you are for nuances between varieties of apples. I'm swapping a Marantz 8b and a Schiit Aegir on a 90db efficient pair of vintage KEFs. They both sound delicious.