Recommendations for used CD player


I'm looking to improve my sound by adding a CD player to my system.  I'm currently now just using a Yamaha DVD player along with a Yamaha Aventage home theater receiver (which uses ESS Technology ES9006 SABRE DACs).  I use the receiver as a pre/pro with a Threshold S500/II amp and B&W 802 Series 2 speakers.

Right now I really like my sound and I've read these DACs are fairly high quality, but wasn't sure if I could get improved sound by adding a used, higher end CD player and possibly outboard DAC.

No SACD needed, my budget is about $400-500.

Thanks.

dastro
I have decided to keep using my Yamaha DVD player as my CD player since I'm back to using the 802's.  Frankly, they sound wonderful together- there is no need to try to warm things up.
I think some isolation for the AC to your DVD player would be very worthwhile.
I bought my daughter a Marantz CD6006, running just over $500 new, and I compared it to my Sony EX player that was several thousand in price, and they sounded very similar. My feelings were a bit hurt that her $500 unit sounded almost exactly like mine! The rest of the system was exactly the same. When I bought that Marantz, I read consumer reviews on many CD players in that price range, and it had the best customer rating as well, as far as dependability and lasting past the first year. Worthy of consideration. 

DVD is a lousy transport with high jitter and harmonic distortion it's better to use dedicated CD transport without inner DAC such as the Cambridge Audio CXC or Cyrus CDt .