Why do amps sound different?

Tvad, it can be (usually not clipping though), but there are other things that can do that that I would think would be more likely. Resonance excited by volume in the system is where I usually start when looking to kill sibilance. Cartridge setup, driver resonance, odd microphonics and cables are a few of the things that I have found to be more common.

Amplifiers and preamplifiers be guilty too so you have to be suspicious of everything.

In my audio experience, the main issue with amps is the unpredictability of how the output characteristics of an amp will affect the acoustical result of the loudspeaker. An effective way to reduce impact of an amp’s sound signature and get consistent and very satisfying results even with cheap amps is to let it drive directly the easy load of the speaker, removing any crossover components downstream of the amp. The influence of cable and connector impedance will then also vanish to almost inaudible levels. You then have to invest in multiple amps and do the equalizing and crossover upstream, but after having heard the results of doing so, you will probably never want to go back to playing the insane, frustrating and never ending quest of finding the "perfect" amp that will blend best in an inherently imperfect system architecture.
/patrick

@path73 John Otvos did that with his Waveform speaker. He used a custom-made three-way active x-over made by Bryston and three Bryston stereo amps (one per driver). No internal passive x-overs! Excellent SQ! And this was 30+ years ago! Now apparently unknown by the younger audiophiles! Remember this name: WAVEFORM!

Most electronics (amps, preamps, DACs) have been essentially sounding alike for the last 20+ years! Contrary to what the "golden ear" crowd claims! The marketplace dictates good sound and weeds out poor designs (except for some tube gear!). You want a better "sound"? Well then, buy a BETTER pair of speakers!