What doesn't sound good? No bass? Not clear? IMO, the 1500 should be a decent CD player, so I would suspect there is a setting somewhere that is wrong in the player or possibly on the receiver that you've missed (it happens). I would not expect a CD player to solve the problem, unless it is a problem with the player itself.
I had the CC4000 and I hated it (have not heard the 4300). Sound wasn't as good as I had hoped, and then it went and died for no apparent reason after just 5 months, taking one of my CDs with it. I replaced it with the Sony CA70ES and it actually sounded much better, which I didn't expect, and I then replaced that with the 222ES for SACD.