Amp makes clapping noise

I had a Peachtree Preamp and Amp that worked perfectly well and recently sold them here. The buyer hears a clapping noise when connecting the amp to his speakers. The preamp or other sources are not connected. I did a FaceTime call and it does happen. Any ideas what the issue could be? He is connecting them to Snell speakers which he says works with his earlier integrated amp. Any input is appreciated. 
my amp gives me a standing O when i play vinyl

and it boos me out of the room when i stream spotify

sorry couldn’t resist :)

sounds like that class d amp in the peachtree has bit the dust and is oscillating ... just a guess
The amp or the speaker is clapping? There are cables between the units? There are cables from the preamp. I'd make sure EVERYTHING was hooked up, pre amp to amp amp to speakers, and nothing was touching or BACKWARDS.  Then test. Removing ONE cable at a time, and retest, if you don't see something.

Backwards or touching is my guess? Bad cables, jerked loose when pulled and put back into service, on the newer gear.. What did work great may have been manhandled and caused something to pull loose or cause a wire to touch somewhere..

Thanks oldhvymec. The sound comes from the speakers and not the amp itself. The pre-amp was not connected to it. Just the amp and the speakers.

I'm wondering the same as well if its an issue with the cables or the power outlet. Tried searching online but have not seen anything related to it. I'm confident about the amp and the shipping boxes themselves did not have any damage. 
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Well what's up OP? Get it solved?  I sure hope it's not a problem. Why would it develop a problem, from being shipped? That would be VERY rare, I would think, well actually, know.. If it's packed right, I've NEVER had a shipping problem, PACKING yes, shipping other than the wrong address or lost, no..

Unfortunately no, the buyer is an elderly person and not able to try different options like cables and speakers. He is sending it back. I had used the original box and packing materials. I will have to try it out for myself when I get it back. 
CRAP, that sucks, your a good sport about it, though. All in All, you're better off. Shipping tight is always right... If it moves inside, it's packed WRONG. LOL Peanuts, are an auto refusal at the DOOR.
I see peanuts it send it back... Funny to, I ALWAYS tell the seller too.

I've had them show up here and ALL the delivery guys know, "Refuse, right" They look for me now... NO PEANUTS, Even when shipping peanuts, NO PEANUTS.. No Yoko Ono either... Just sayin'

As an update, I received the package back from the buyer, and as expected work perfectly fine. I was confident about it all along it may be something within the buyers other components that's causing his issue. I will have to refund the payment but the question is am I within my rights to ask for the fees I've paid to Audiogon and PayPal because there was no issues with the amp and preamp? Its less than $100. Didn't want to get a negative feedback for no fault of mine. 
The truth always works for me.. Ask the guy if he thinks it's fair?
Did YOU offer a no question ask, money back deal? 

Fair questions for fair people.  Feedback works both ways.
Does for me anyways.. Some folks you can't do business with.

Come on you broke the key off in the lock, how is that my fault?...
Ok yea, I've hear it all.. Oh and it was a piece of sh%t to boot.. LOL