Best in my experience-
Audio Research for technical Q/A and repairs, Upscale Audio for customer support and expertise, John Rutan at Audio Connection for customer support, expertise and repair issues for equipment they did not sell me.
Worst ever-
Pro-Ject who did not answer any of my emails regarding the reliability of their newest CD Box RS2T, but did find time to tell me in an email that I was a pest and to leave them alone. No kidding...