Many good suggestions above. In the quest for better digital sound, I've gone to an aftermarket cord (without spending huge $$$), damped the chassis of the player extensively with industrial floor tile, addressed support and isolation, and used high quality power conditioning.
Something that gets little mention and is probably grossly underestimated and receives little recognition (probably because of its low cost) is the Quantum Electroclear line filter, available for $40. For $40, this is probably the bang for the buck champion in eliminating/reducing the edge from digital.