Low level noise from spkr when nothing is playing

ground loop. Lots of threads. Had the same thing in my system.

Agree with Marakanetz. If you can only hear it if you hold your ear up to the speaker, then it doesn't really matter.

Off hand, I would try switching the preamp feed so that the center channel amplifier input is coming from a different output of the preamp. If it switches speakers, then perhaps it's a noisy channel from the preamp. If it doesn't change, perhaps its the amplifier center channel.

But honestly, what does it matter? You can't hear the noise except in a situation that is not normal (ie. you do not commonly listen with your ear to the speaker).

For what it's worth, some gear is just a bit noisy and I could hear some noise with high efficiency speakers on quite a few amplifiers if I held my ear up. I just ignored it.

It does not change my overall listening experience and I appreciate your input. As you all know, it is easy to be overly focused on every little thing. At the end of the day, I love the sound.

Grimace, I do not know what you mean by ground loop, lots of threads? How did you fix it in your system?

I had the similar issue with my AV receiver, except that it suddenly developed in my LF speaker.I ignored it for a while, but within a short time more audio problems developed.

I ended upn shipping it back to the distributor for a warrnty repair - some of the circuits had been fried and new parts and circuit boards inserted as replacements.
Speculation is that a sudden power surge (repeated) caused the problems.

FWIW ....