used high-end DAC or affordable newer model?

I have an old adcom 575 cd player that i will be using as a transport and i was wondering if it would be better to do with a newer dac like the MSB link III or Channel Islands VDA-1- or should i go used high-end such as the EAD dsp 9000 pro now on ebay- it seems that the older high end dac's can be had for the same money as the newer affordable models but what are the sonic differences?
As, maybe even more important, is your transport. No matter which DAC, it will only be as good as the laser /transport reading/sending signal. Consider soomething like a CEC belt-drive transport/cd player. Later add a hot dac then you've have a world-class digital front end. Northstar has really nice sounding dac that is capable of 24/192 playback.
Thanks for your responses. Interestingly, when i called Tor at Conrad Johnson (I own a CAV-50) and asked him this same question, he said forget about DAC's and go for a new DVD universal player such as the Marantz that sells for $1600 or even the Pioneer elite for $750- but do they really do as good a job with music as CD players or DAC's? feel free to respond.
One more thing, i'm having trouble finding any info on the EAD DSP 9000 pro HDCD(there's one on ebay)- I've found alot about the MKIII
version, but it seems an altogether different animal- anyone know about this unit or how old it is- Thanks.
My advise is a bit different. have been recently surprised like professional audio DAC can easily outperform the highly priced higears.
My personal experience is that a 300 USD product from the pro market can easily beat a 5 years old 2000 USD gear.
Believe me it is a colossal audible difference, sister ear proven!
Quite a lot reported by others in this forum too. Product like ART DI/O seems to sound splendid. In my case I have a Mindprint DI-Port that in audio pro tests was not too far from Apogee top of the line converters, and anyone that know this name understand the point.
Give a try to one of this cheap stuff, no risk of smash, only good surprises.
If need more info contact me