You're certain to get better CD sound from the decoding on your 6200, rather than a SD220. Do a search on DVD players with decent CD sound and you'll get about a million results...
Mate - for that sort of budget you're not going to get better PCM conversion unless you buy a dedicated CD player...and even then not necessarily...stick with the 6200...
While I won't deny the fact that a CDP connected via analog sounds different (I don't say better!) from a DVD connected via digital the limiting factor is and still will be the AV amplifier/receiver itself. My "audiophile" friend and me couldn't hear much of a difference between his CDP and my DVD connected to a Yamaha DSP-A1 - and when it comes to common Pop/Rock recordings ... well, the whole thing becomes pointless anyhow.