When did vinyl have 3 channels on it? or 2, for that matter? Discrete?
It was not amps or pre that had the limitations as you can line up any number in a row, but software.
A 3 chan analog recording would reproduce music better than an encoded software enhanced recording.
Actually, what is needed is three of those speakers with the two ch and 3 ch ability to be switched and behing acoustic curtins so you are not biased, then we can see which setup is more accurate, more realistic, etc.
Your proposal with different speakers will tell not much other than speaker differences. But, even that can be tested though, DBT, of course.
2 ch is history. It cannot capture nor reproduce what a multi channel can.
But, if you like the 2 ch, no problem.
You have 2 ears, in a live performance the performer is playing in front of you, everything else you hear is caused by the enviorment surrounding you. Movies, i agree surround and multi chan is the way to go, but to reproduce music it dosnt work.