How big of a difference do amps make?

Depends on the speakers. Some just can't make use of extra power. Matching amps to speakers is more important.

Cue Ralph's link to the "power paradigm"...

Congratulations Elizabeth. Don't drink the Kool Aid. It's not what we hear, it's what we think we hear. Often, cause and effect are not as direct as we assume.

Charles1dad:

I have no axe to grind on either side of this argument. Who am I to say what someone else should prefer? Just appreciate someone standing against peer pressure.

The point I eluded to was that the ears hear but the brain interprets. It's a filter and it's called psyco-acoustics. For example, if a vocal frequency range is diminished in comparison to instruments, that can just as easily have the illusion of more distance or depth. For stereo, psyco-acoustics are fundamental. Nothing to do with tubes versus transistors intrisically.

In the projects I've done, like comparing Bessel to L-R filters, it's much more of a trick to disassociate the interpretation to identify an actual distortion or frequency response or whatever. Still not good at it.

Apologies for getting off track.