On Line Audio Mail Order Retailers

I've always had top notch service from Music Direct and Audio Advisor. 

I would classify B&H Photo and Adorama as primarily camera, video and photography retailers.  For audio, I turn to Music DIrect, Audio Advisor and Crutchfield first because that is their primary raison d'être.

Aside from that, I have purchased from all of them (but primarily camera gear from B&HPhoto and Adorama) with no issues and excellent customer service.

Have bought some gadgets and accessories from B&H and Newegg. Both have been excellent with pricing and the transaction process. Both offer great specials frequently. Purchased some APC and Cyberpower battery backups at below 50% of retail. Both are fairly liberal with free shipping as well.

Besides Music Direct, I've also had great service from B&H and Audio Advisor. If you find yourself in New York it's worth a visit to B&H, a giant fantasyland of gear...audio, photo, every kind of electronics you can imagine, with a staff that knows its stuff. It's pretty much the most fun you can have in Manhattan. 

I think most of the online retailers who sell high-end stuff have people who can give you support when you need it.  It's kind of strange though - Most of these online companies charge full list for their products.  When I go to a brick and mortar that charges full list I get a demo and setup in my home.  These online guys give you none of that and still charge full list for the most part.  But to answer your question, I've had very good dealings with Audio Advisor and Music Direct.  They had people available to answer my questions about the products and were very courteous and knowledgeable about what they sold.