I don't mean to be rude, but I'm very skeptical of these sort of claims. To illustrate: I've walked into a friends house and thought "it sounds like XXXX has new speakers... Klipsch?' and been right, at least regarding new speakers and sometimes the brand if they are distinctive (like Klipsch).

I've never walked in and thought, "hmmmm, sounds like Tom has a new HK amp".

So I suspect that while they may very well sound different, the difference is (I suspect) subtle. There have been plenty of blind tests that indicated audible differences in amps, but I've never been just blown away by an amplifiers distinctive 'sound'.

The comment regarding amp speed makes no sense to me - either it can reproduce an 18kHz sine wave or not. Or is that not what you mean?

Charlie