I need some CD player suggestions please

I am currently using a many year old Harmon Kardon 5-CD player that has served me well but it is finally time to upgrade. The rest of my system is a Pioneer Elite receiver that basically serves as a Preamp for the system. Then I have a Citation 7.1 power amp for 2 channels and then 2 more channels or amplification are handled by a Legacy/Cota 2 channel amp. The only amplification being done by the receiver's 140 WPC is the center. Speakers are Legacy Focus front and Silver Cinema II Center Channel.

I already have a Samsung 3600 Blueray so the new player only needs to handle CDs for 2 channel use. I have played around a bit listening to CDs in the Kardon and the Samsung CD/DVD player and I am unable to discern any difference at all.

So either they are both 'bad" enough not to show any difference or my ears are not good enough ( at nearly 50) to hear the difference.

I would really like to find a 5 cd changer if possible because I like the fact that it allows me to cue up a few hours of music, but I am willing to get a single if it really makes a big difference.

For budget I would like to buy used under $600. Is there any hope for me to find something decent for this price?