Here is a challenge then.
If, in a controlled experiment with all variables accounted for (incl. differences in frequency reponse and within the power range appropriate to the amps) under instantaneous A-B relay switchover, driving any Harbeth speakers, if you can positively identify an amplifier by sound alone, I will give you, FOC, a pair of brand new Harbeth speakers, up to and including a pair of M40.1 in any veneer you fancy.
I am quite confident that under controlled conditions, these fabled amplifier differences disappear and that I will never be parting with my money!
However, I don't have the time to play around. You have to conceive of the test, design the switch over system and bring it to us here and we'll cooperate fully. There are plenty of examples of carefully constructed tests over the past 30+ years to draw on that meet my critera, and every one of them comes to the same conclusion. As far as this 'amp matching to Harbeth speakers' issue goes, it is a non-issue. As dead as the dodo. I cannot comment on the amp matching for other speaker brands. We take care to make our speaker an easy load: other speaker designers may be less consumer-focused.
NO CORRESPONDENCE PLEASE - CALL ME WHEN YOU HAVE THE WHOLE PLAN EXECUTED!
Amplifiers should be selected not for "sound quality" (whatever that is) but for facilities, design integrity, durability, after care and likelyhood of being able to source service parts in 5 or 10 years. Also, if you're really serious, a quick peek at the financial standing of the brand might tell you if they are likely to have the financial resources to weather the economic downturn of the next few years which is effecting the whole consumer electronics sector. Some of the most likely surviving (UK) brands rarely advertise, rarely exhibit, have relatively old-fashioned designs, use standard parts, have been around for a generation and are rock solid businesses. They deserve to be respected and supported because they will be there to look after you in 10+ years.
There are some very difficult times ahead for the consumer industry: now is a time to be cautious.
Alan A. Shaw
Harbeth Audio UK