I would go further, to say that even if everything is done "properly" to do such AB compare, expectation bias will likely still play a strong role. That's why SBT/DBT would naturally be more convincing.
If you end up using REW, plot a FR graph from you mlp, one speaker at a time with no EQ, no DSP, then leave everything exactly the same including the mic position, but simply switch to a different AVR, amp or preamp but make sure you volume match first before doing another sweep. I guarantee you will see the two FR graph look very much the same, like overlapping on top of one another if you apply even just 1/48 smoothing so your eyes can see better. Now move the mic 6 inches in any direction, sweep again and you will see a very different picture. What would that tell you? You'll be the judge.. I have done such experiments using my different speakers, avrs, prepros, preamps, and amps so I know the pictures.
@AcuDefTechGuy, do bad you are not as crazy as I am, but I do wish you would do some of such experiment because like me, you are at least crazy enough to have owned, and I assume still own quite a few avr, prepro, amps etc., so you are well equipped to do it. RichB done it and he did find some difference between his ATI class D vs AB amps iirc but I can't remember the reason(s) for that.