Hi.
It's a funny one isn't it.
I would like to think that the amp just passes the signal straight to the speaker binding posts untouched but I think you may be right....
I used to have a Yamaha AS2100 and it had the most beautifully designed analogue stage I've ever seen!
Both channels were separate, balanced and completely clean.
Lovely sound and those big Mosfets! Wow.
Should've kept it but it was an absolute beast!
I'm going to research this but I have a feeling its a subject that has no easy answer!