I don't advise using CD players anymore, but here are some other great tweaks if you do:
1) Put a treatment on the Disk, like Ultrabit platinum plus
2) coat the top of the disk with a rubbery paint to reduce vibration while spinning (this is the best tweak)
3) put the disk under a fluorescent light for 20 seconds just before playing
4) use a demagnetizer to remove magnetization and charge
Steve N.
Empirical Audio