And what that testing demonstrated is that when an amplifier is driven outside of its optimal/rated operating envelope, it "misbehaves" and that misbehaviour, varies with different amplifier designs - which makes the differences audibly different.I have no idea what you are talking about. Here is an example of ABX testing that was done by the very people who popularized such tests:
Double Blind tests *did* show amplifiers to sound different
In many online debates, position taken by some that when amplifiers are used that have flat frequency response and low distortion that no double blind tests have shown them to sound different. Well, I managed to dig up a 32 year old test that says otherwise. What is fascinating is that one of...www.audiosciencereview.com
How is this not "comparing one device to another to determine if you can tell them apart?"
Similar tests, which used easier to drive speakers (not ones which at the top end drop down to 1ohm or less!!) - and stayed well within the optimal operating envelope of the amps being compared ... found that they all sounded identical....
Yeah they CAN sound different - but if the amps are matched to the speakers... no they don't sound different.