I use my DVD player to play CD's. It is setting on a wire rack shelving unit that vibrates pretty significantly when I turn up the volume. I got a hold of some scrap, closed cell insulation at work. It's about a 1/2" thick and feels kind of like those gel filled wrist pads for keyboards. I put a small square under each foot of my Pioneer DV-525 DVD player. The overall sound quality is much better. The only way I can explain it is maybe the vibration was causing a lot of read errors which caused a harsher sound. I've seen this type of tweak mentioned before, but didn't think there was much substance to it. If you haven't tried it before, you might want to.