Do you mean "noise floor" by any chance? I'm not going to explain it well, but it's a term used to describe the background noise of the recording. For example, it might refer to the noise that a microphone preamp makes, tape hiss on an analog recording, static on an LP, etc. A digital recording made with excellent mics and preamps should have a much lower noise floor than a recording made on a cassette player with a cheap Radio Shack mic. Some components also add noise when playing...certain turntables, certain tubes, transformers, etc. The lower the noise floor, the more the actual instruments and voices stand out against the background.
As far as the stone slabs go...your guess is as good as mine. People do it to dampen the vibrations, but I have never tried it. I think it's one of those things that would work for some and not for others. I suppose it couldn't hurt...or could it?
As far as the stone slabs go...your guess is as good as mine. People do it to dampen the vibrations, but I have never tried it. I think it's one of those things that would work for some and not for others. I suppose it couldn't hurt...or could it?