Best way to A / B test amps? Use a switch?

Everyone knows it’s BY FAR better to A/B test with instantaneous switching than relying on memory and what you think you heard.

Well, no, that is not the case at all.

First of all what you suggest is impossible. Even instantaneous switching still the goal is comparing. With what? With what you heard. When? In the past. Where’s the past? In memory. Nowhere else.

You simply haven’t thought this one through. Not at all.

Which aspects of the sound? Well how do you even begin to answer that one? By thinking over the different aspects. Which involves what, again? Memory.

All you’re doing with this instantaneous switching malarkey is moving the proverbial runner halfway to the finish line. You know the story, right? To get to the finish line he must go halfway, then halfway, then half of that.... never gets there. When in reality, WHOOSH! Right on by.

That’s exactly what you’re doing. Inventing some nonexistent constraint, insisting its real. When in reality, WHOOSH! Right on by.

Besides, what about warm-up? Break-in? Acoustic treatments? What about differences between recordings? Do you now require duplicate identical turntables just to decide which LP is better?

Its really just beyond silly.

Especially since, if the difference isn’t big enough you can still be sure after the 5 minutes it takes to change something out, then why would you care anyway? Answer me that one.

I would have thought there was something practical on the market already.

Well, there would be. If it would serve any purpose. Which it doesn't. So its not.

But seriously, the question stands: If you can't be sure after a few minutes then why do you care?

What about differences between recordings? Do you now require duplicate identical turntables just to decide which LP is better?

Absolutely.  Switching is just a distraction and works against obtaining whole picture.  In order to get whole picture you need to listen to many recordings over period of time.  Perhaps because of that many companies, like Benchmark, give free 30 instead of few days evaluation.

bring them to my house

Very good points.  Some of which I have considered but not enough.  

I still think the audiophile thinks his aural memory is much keener than it is and not susceptible to audio forum interference/influence.  But, you're right saying that the "over time" part is also very important.  And there are downfalls to switching as well.

The other part of the issue with me personally is I don't have time to deep listen for hours on end and my environment changes quite rapidly.

I have done extensive A/B comparisons between equipment.  Be it pre-amps, amps, DACS, etc.

My experience is to play a favorite song (say CD) at the volume you like.  remove the CD and play a white noise CD and measure the DB level with a meter.  Then swap the piece of equipment with the one you want to test.  Again play the white noise CD and adjust the level to where it matches the level of the previous unit. Record both unit's levels so you know where to set them when listening.

Making sure the levels are matched before comparing is absolutely important.

Now that you have established the two levels, go for it.

Listen to the first unit with music you know.  Then swap the new unit in. making sure to turn the amps off if swapping amps or mute pre-amps if swapping other stuff.

This has worked very well for me in making purchasing decisions.

enjoy