Hum sound ..is it me or is it you? LOUD hum in system


I sold a classe SSP-30 preamp 2nd week of April. worked fine. I played with it . zero noise at all.
sold it to get a simpler dedicated 2 channel preamp.

nearly two weeks after it was delivered I get an email saying that when the classe 30 is installed there is loud hum...but when its not there is no issue. 

that is all I am told..and "I want to send it back"

im kind of agitated that buyer took his sweet time to get around to checking it out or whatever.  Not sure what to do or what I can do. I told him to send it back so I can see it.

my question is, I read lots of info on grounding loops and funny noises .   because buyer claims he has noise does it leave me any other choice but to take it back?

I used the pre before I sold it for this exact type of reason.  i just didnt take video.   im not to pleased with the extra long delay neither. seems like if you spend that much money on something you check it out right away. it doesnt take a lot to hook up a preamp.

i find it hard to believe a preamp of this caliber would even have ground issues.

I dont know what to do. I feel like I am at this guys mercy no matter what?
gentlejax
It looks like you have no choice but to have the buyer return the preamp for a refund. When you get it back check it out then relist it!
Even if there is a noise, it may not have anything to do with the preamp. At the very least I would have gotten a very detailed list of his system. My best guess would be that nothing's broken, and its a setup issue. Although, one potential problem could be the RCA connectors on the SSP30. They break very easily. If that happens to be the problem, Classe will almost certainly repair the unit under warranty, even if its expired.
Ask him to use a cheater plug on the preamp and plug directly into the wall. Tell him this will test for a ground-loop in his setup. If there’s no more hum, the preamp is probably fine.