Originally Posted by ClarkeBar /forum/post/12998450
If it doesn't increase with volume then the buzz is most likely internal to the amp...probably low level transformer hum being passed to the speakers. I have experienced this with every toroidal amp design I've had including Parasound. I really don't mind it as long as it is inaudible to me at the listening position...and in fact it is inaudible up to about a foot away.
In my experience bad/failing capacitors can also contribute to hum.
PSAudio is redesigning the Humbuster early this year.