older CD transport vs newer ones.

I second sns with the Mark Levinson #37 drive and Philips CD-Pro transport - I used this drive built in Madrigal Proceed PMDT in combinstion with Reimyo DAP 999 EX Ltd. for many years and it sounded great, nothing came close.
When the laser finally died I tested a lot of different CD- and DVD- drives as transports only (Denon, Primare, Micromega, Electrocompaniet, PS Audio PWT, TEAC) - nothing showed the same sonic quality.
Finally ended up with Audio Research Ref. CD9 SE carrying again the Philips CD Pro-Transport, which is said to be one of the very best drives ever built.
The Project CD-Box RS-2T sounds interesting as it carries the Stream Unlimited (ex-Philips Engineers) CD-Pro 8 transport - this company also supplied the laser drive for the Wadia S7i which is not a bad reputation at all.
Furthermore I second charles1dad that the better the transport the better the sound! 
Probably you can find an AR Ref. CD8 used with Philips CD Pro Laser mech. and use it as a transport only with your Rossini DAC (I clearly preferred even the AR Ref.8 to the PS Audio PWT, the Ref.9 is even better than Ref.8 IMO)

@ggc: you're absolutely right with the VRDS and VRDS Neo drives - I wanted to buy a Wadia combo of 521 DAC and 571 transport - there was an 24/192 upgrade announced for the DAC 521 - I was waiting almost 2 years as I wanted to buy most recent products - unfortunately Wadia stepped out of the hghi-end business with those products before.
The Wadia S7i player had built-in the better 24/192 DAC but according to Wadia engineers the drive itself was not on the same level as the 571 transport.
So I went with the AR Ref. CD9SE and the Philips CD-Pro transport.