SA 200.2 ES solid state power amp

[Dilettante]

Hey guys,

I bought a slightlly used SA 200.2 ES power amp. it was manufactured in 2019 and this is a newer ES current model, not the original non ES one.

When I first turned on the amp everyting was fine and was quiet. But when I used the amp to play music for an extended amount of time like some 6-7 hours at moderate volume levels I started to notice a slight buzzing / humming noise coming from the right speaker (only right channel) and pretty soon the buzzing / humming got progressively louder and eventually became extremely loud. again it's only in the right channel speaker and the left channel remains quiet.

I know for sure it isn't the preamp or the source component cause when I swapped and changed to other amp, which is a Classe Sigma Amp2 class D amp, everything was quiet. I've been using this Classe Sigma Amp2 for 5 years and never had buzzing / humming issue. So, gotta be the Cary SA 200.2 ES amp.

So, I sent it in to Cary for service / repair last week and they have received the amp on monday (2 days ago) and they have put my amp in their listening room and have been playing music non-stop since monday for 48 hours and didn't hear any buzzing at all in the right channel speaker. So, they couldn't duplicate that buzzing noise in the right channel speaker.
Very strange.

Don't think it's an induced noise or AC related noise that I was hearing on the right speaker cause it was quiet when I first turned on the SA 200.2 ES amp, and not until few to several hours of use that the loud buzzing started to appear, and it's only in one channel (right channel speaker). And when I had my other amp, which is a Classe Sigma Amp2, everyting was quiet no matter how long I've used that amp for.

Any thoughts guys? I've never experienced this bizzare experience before. And my Cary SA 200.2 ES amp was manufactured in 2019, so it is failry new amp. Thanks in advance everyone.