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
Paypal sent me a email this am to confirm that the buyer wins.

the reason was listed as "because"

how unprofessional sounding pathetic explanation.  I'm not at all surprised because everyone knows they side with the buyer rmost of the time.  On eBay you can't even leave feedback for the buyer. It's a unfair system. 

I am surprised at the childlike response for the reason.  It just said "because" in small letters half the size of the rest of the entire email. 
dont worry I dont need to sell anything here.   what make me mad though is I have had time to listen to it now and adjust it and its much nicer than the adcom I had and about as nice almost as the Proceed I wish I had kept that I also sold on here but got no feedback on.

except now I have dings on top where there were none thanks to bad buyer
This was my 2nd transaction...but I have 707+ on ebay
gentlejax, seems like you did everything right, and nice work on the negative feedback you left for ehanee. Now that's 3 neg. for him. Looks like he buys items every week, maybe to flip them on Ebay.
man this guy is something else.  I got a notice from Audiogon he is disputing his feedback.

YES, after he forced a refund and sent me back a unit physically damaged he is now lying and tying to get his negative feedback taken off.

He is completly shameless. 

the unit is now in my system and running fine.

talk about adding injury to insult.