Manufacturers with Excellent customer service

I will also add Jeff Smith at Silversmith Audio as he went to great lengths to allow me to try his new speaker cables.  He even made a second pair of adapters to allow biwiring to my speakers and got it out to me in 2 days while making it.  Always stays very positive in all communications and is ready to talk shop.  

In my personal experience, Pass, Bryston and Bricasti have been excellent 

The most underwhelming experience was from a company long gone- California Audio Labs. 

Rogue Audio

I sent a Rogue power amp in for an upgrade and it got severely damaged on the return trip to me. Mark O'Brian  (of Rogue) sent me a new amp and I did not have to pay a penny. He was very nice about it.

Ps Audio. 

Not a manufacturer, but Kevin Deal at Upscale Audio. I also second Vlad Bazelkov at Audio Mirror. And add Kara Chaffe of Dehavilland. Also Egglestonworks (speakers). I have dealt directly with all of these folks and the service was first-class, as expected.