Best CDP under $500?..... Used market

Cal Audio CL-15

You just might find a Shanling CD-T80 or (a bit less likely) a JAS Audio Musik 1.2 for your money, and either of those would compete at the top of the class.

CAL Icon 2. There is one listed here. I had one back in 1995-98. I replaced it with a Meridian 508.24 and couldn't say which was better. Not to much glare or tizz (not the most resolving either, but very pleasant).

If it were me, I'd keep the PD-65, sell the NAD preamp and with the proceeds + the $500, I'd buy a nice tube preamp. The NAD pre is the weakest link in your system, IMO...good luck.

Two weeks ago I would have agreed with all these recommendations - but not now. I own a Cambridge Audio Azur 640C v2 player and thought it was a good but not great player with magnifying glass resolution, but a somewhat bright and overly analytical presentation. Then I auditioned it with some Shunyata power cords and a very capable Sim Moon I7 integrated/Dynaudio Contour stand mount combination and WOW! The player did not seem out of place in this company, and the better the cord feeding it, the better and more at home and balanced it sounded. Outstanding Resolution was still present, but also bass and warmth and soundstage too. I ended up buying a Shunyata Diamondback cord for the Cambridge CDP and am enjoying music like never before.

I now think this player could provide a bridge for the upgrade path from budget gear to higher end amps and speakers and all the gear to support and connect them. You can get a 640C v2 new for $400 at Audio Advisor right now (http://www.audioadvisor.com/prodinfo.asp?number=CA640CV2), and probably for significantly less than that used. Buy a good power cord or use one you have on hand and you are in business for under $500 (make sure you get a v2 model because there were significant improvements between versions 1 and 2).

Your Pioneer may be slightly warmer than the Cambridge, but listening to the 640C fueled by a quality power cord and played through a decent system will reveal detail, PRAT, air and a natural warmth and bass line that will throw your previous cost benefit equations into disarray, and perhaps wondering what to do with your old player...