Buzzing sound from Peachtree Nova 150 - anybody else had similar experience?

I bought Peachtree Nova 150 around 10 months ago. While I was very satisfied with the amp to begin with, I slowly started getting more bothered by the high frequency buzzing it makes when it is powered on. The sound comes from the device itself, not from the speakers, very high frequency, similar to the sound from old CRT screens. It is very noticeable when standing close to the device, but if it’s otherwise quiet I am also hearing it as long as I am in the same room. And though I probably will be able to ignore it while playing music, it does bother me as long as there’s a pause in the music or while watching movies. I don’t think I am being overly sensitive, I have other electric devices that make far more noise, like my projector or hard drive RAID, but it is just the high pitched whine from the Peachtree Nova that bothers me. With simple measuring software on my phone, the sound is measurable from about 1 meter from the device, and shows up as a sound with a peak of 8 kHz and a smaller peak at 16 kHz.

After I sent complaints to the dealer I bought it from, the the amp was sent back for repair. Twice. Both times it came back with absolutely no changes to this issue, as far as I can hear. The guy who did the repairs measured the sound after the last repair to be "significantly reduced". But I can’t hear any difference. He indicates that the current in my house can be the culprit, but I have also tried it in my office building, both in grounded and ungrounded outlets, without any changes to the buzzing. What I haven’t tried yet is any kind of expensive AC filter to deal with noise. Could I expect that such a filter (fx IsoTek Corvus) would make any difference here? I am hesitant to try it, since I wouldn’t expect that a relatively expensive amp (for me) would need such a thing just to function properly.

That the repair shop claims the sound is "reduced" indicates to me that some kind of buzzing from the device itself is to be expected, just that it should be at a significantly lower level than what I am experiencing. Is this on par with with what other owners of Peachtree Nova have experienced - could I expect it to be dead quiet?

It seems to be the same issue discussed in this thread.

I sympathize, kevinjkim, but the issue in this thread is not the same as what you describe. I make it quite clear that I am talking about a buzzing sound from the actual device, not through the speakers or headphones. It was very irritating, to be sure, and enough for me to return the amp and not to buy another peachtree product again. But what you describe is worse than that.

I do hope that you can get it resolved - I got great contact with Christian Ballard at Peachtree, through the normal support form. For me it didn’t work out in the end, because they seem to look at a slight buzzing from the amp itself as normal. But what you descibe is an issue that they do not see as normal.

Anyways, the experience didn’t just scare me off Peachtree amps, I more or less gave up on brand new stuff for the time being, at least class D amps, and spent some of the money on a used Accuphase 406v instead. This 23 years old amp has nothing in common with the Peachtree nova, of course, it doesn’t even accomodate a DAC board, but sounds so extremely much better with my speakers that it’s hard to believe.
Kevinjkim, just a thought... I would try using a power conditioner. Depending on the region and country, the power can be “dirty”. I had an amp that hummed a few years back, uses a power conditioner and it resolved the issue. Many amps have a power conditioner built into the unit but maybe not Peachtree.  Btw, does the Peachtree support both 110/220 or are using a step down transformer? 
based on your description, it sounds like a cap is going in the switching power supply.

I'd contact them and arrange for repair.

Transformer buzzing is relatively low frequency. If it sounds almost like a whine, it's more likely to be an issue with the switching power supply. Get it fixed.