You would be better off to buy a new stand alone DAC, with newer chipset, and use your existing disc spinner as a transport. I would suggest looking at a Musical Fidelity M1 DAC which I believe is just a bit above your budget at $600, but worth the stretch if you can make it. The plus, beyond just the sound, it the flexibility it will give you to expand into digital music.
can i improve my system with a better cd player?
I upgraded just about everything except my cd player. I just use my old sony dvp s7000 as my cd player. In the past I thought all cd player were the same until yesterday when I tried using my ps3 as the player. I instantly heard a big difference. Now I'm thinking I can actually improve my sound by buying a new player can someone recommend something under 500 buciks? I like buying used since my system is dated itself but it still sounds decent to me.