I run an Oppo DV-980H as my digital source, and like it quite a bit. If there's one gripe, though, I have to say that the thing is about as sturdy as a carnival ride. Shortly after setting it up, I sat the feet on poster putty, partly to fight vibration, but mostly so it wouldn't move when I pushed a button on the faceplate!
Some discs, for whatever reason, seem to really crank the Oppo (lots of "buzz" from the transport). I do a lot of low-volume, late-night listening, and buzziness can get quite distracting. So, when I stumbled upon the Audio Additives damping plates on Music Direct, I thought "what the heck, I'll try it". For the unfamiliar, they're thin sheets of stainless steel with adhesive on one side and a proprietary 3M damping material on the other.
Well! I must say that this has been $20 well spent.
I bought 2 4x6 sheets and stuck one to the inside of the top cover. I cut the other one up with regular scissors (I didn't damage the blades. YMMV) and stuck several pieces in the "transport area" on the underside of the chassis, with one larger piece in a depression adjacent to the area under the transport.
I won't claim night-and-day sonic improvement, but detail retrieval has improved. What's really encouraging is that the discs that used to get the player all wound up are now timid by comparison. With previously "quiet" discs, the transport is now vanishingly so.
Time will tell if these little guys are improving sound across the board, but, for now, the electric weed whacker has been tamed.