I have not had a lot of experience dealing with manufacturers of equipment I've bought used on Audiogon, but I have dealt with McIntosh and PS Audio and have nothing but good things to say about the experiences.
I purchased a McIntosh MAC6700 and though it was connected to an APC UPS, we had some sort of power "blip" while it was playing, corrupting the firmware. I called the local dealer and they sent out a technician to re-load the firmware, and I was back up and running. Of course this was a service I paid for (the unit was not under warranty). Prior to that, I was considering purchasing an SACD player on Audiogon where the photo had the serial number blanked out with a slip of paper, contacted McIntosh to see if they had a list of stolen items, and they responded quickly.
As for PS Audio, I purchased one of their DirectStream DACs (new, from an authorized dealer), and they have provided multiple firmware updates on their website and have had questions from time to time and have had the pleasure of speaking with their technical folks, who were very helpful.
I purchased a McIntosh MAC6700 and though it was connected to an APC UPS, we had some sort of power "blip" while it was playing, corrupting the firmware. I called the local dealer and they sent out a technician to re-load the firmware, and I was back up and running. Of course this was a service I paid for (the unit was not under warranty). Prior to that, I was considering purchasing an SACD player on Audiogon where the photo had the serial number blanked out with a slip of paper, contacted McIntosh to see if they had a list of stolen items, and they responded quickly.
As for PS Audio, I purchased one of their DirectStream DACs (new, from an authorized dealer), and they have provided multiple firmware updates on their website and have had questions from time to time and have had the pleasure of speaking with their technical folks, who were very helpful.