Carl, I definitely concur. My 640.2 is a very nice amp and not even one of the higher priced a/d/s amps. Mac is very very nice as well. I have to reserve judgement on Zapco, Xtant, Brax, etc. as I have not heard them all. BTW, Focal Polykevlars are probably the nicest car speakers that I've ever listened to. Amazingly good sound. Taka