I'll give you an idea of my thoughts on amps both from alot of reading and a few blind tests . I feel that amps that are desighned and built well all pretty much sound the same , keep in mind that I'm speaking of amps of similar desighn . Tube amps VS solid sate amps would not be a good example of what I'm talking about .
Dont get me wrong , I'm not saying an amp like the A-500 is just as good as say a Bryston or a Krell for example . What I am saying is that the diffrences in sound will be pretty darn small . Amps are not (for the most part) desighned to add sonic signatures , they are desighned to be neutral sounding. No single amp manufactuer has a silver bullet and a desighn that is not known to all others, so it's pretty much an equal playing field . What differs is build quality and in some cases slightly better parts .
This not to say that buying a Bryston amp is a waste of money . For folks who have the cash and want that little extra gain in sound quality along with an amp thats built like a tank and will work for many years thenby all means go for it. There is a very simple reason why every blind amp test you read about ends up showing that most folks couldnt pick one from the other. The reason is the diffrence in sound is pretty small .
Again please keep in mind I'm talking about amps that are desighned and built well , and that are driven within the're limits . The price of the amps matters not .