Faint buzz in speakers

PS- Modern dimmers, including smart dimmers are not noisy the way the old one's were, mechanically or electrically.  You certainly can have remote controlled mood lighting in your listening room. 

I had a similar problem a few years ago.  In my case I had a subwoofer and I had to ground the sub plate amp to the preamp.  It cleaned it up

Some amplifiers are noisier than others, efficient speakers will bring this out. However, if you can't hear anything from the listening position I would leave it alone and enjoy your music. 

Since "Can only be heard with ear right up to drivers" it is not a "problem."

The solution to the "problem" is simple, don't put your ear up to the driver.

Is it a tube amp? if it is check the bias of

your tubes I just had that problem with

the hissing and cracking out of one speaker

checked everything but the bias and that was it. Good luck