Manufacturers with great customer service

KEF, Both before and after sale. 

HSU Research. Had a plate amp fail after warranty. Although it wasn't free. they did send me a new amp for about half price.

OOPS! 

To my previously posted list - Bryston, Dynaudio, SVS, Woo Audio - I neglected to include Sophia Electric.

Sorry. 

Monitor Audio.  I wrote about this before, but I have (now vintage) 2 way micro towers (very small footprint) that I damaged.  Between my e-mail and woofers being at my door was 3-4 days. 

I was honestly sure they were going to tell me they were too old to have parts for. 

When I reached out to Spendor (A7s) inquiring about my room specs and potential integrated amplifier, they sent me a timely reply with some useful information and context, so thumbs up for Spendor.

Also, I wrote to Cambridge Audio regarding a question about the EQ in the StreamMagic app and they replied immediately with a helpful answer.   So, another vote for Cambridge Audio.