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.
monterey
stands for digital to audio convertor. turns digital data into analogue so your preamp/amp/speakers can make music. they are in cd/dvd/ipods/computers et al. usually they are less than wonderful so in the last decade many companies have been making better stand alone units for audiophiles. for a more definitive answer go to wickipedia. hope that helps
OK now i'm really confused. I read about the digital to analog conversion. So how I do I tell which of my two machines is doing the converting? Is it the sony or the Yamaha? I connected the sony to the yamaha via a toslink cable. With this said, can I benefit now if I buy a new cd player??
I bought a used Dacmagic for around $300 and it improved an older CD changer big time (digital out on the changer). My old but well made Marantz changer has a new lease on life.
I think I'm understanding this now, so a better CD player would only be better if I let it decode the music and then run the music thru my yamaha thru the EXT DECODER as a by pass straight to my amp?