Probably the best service I've had was from Balanced Audio Technology. I got great technical support from Victor for a very minor problem (a dead LED). We determined what the problem was and wasn't, and then he FedExed me a new pair of suitable LEDs, all before they had received my warranty registration. I'm sure he had better things to do.
Best and Worst customer service?
My vote goes for Sonic Frontiers, as Best! I was contacted within an hours, after e-mailing a question. Wery friendly and helpfull!(they can count me-in on the next purchase) Thw Worst? Linn audio! It's been over a month since i submited a Q! I am stll e-mailing the question...i am sort of amused by now!