We have used the Rossini as a preamp with the MC452 , you just have to crank the gain up to 6 volts on the dCS instead of the default 2.0 , when you were using it with a preamp. It sounded excellent, bypassing the C2600.
As I understand it, dCS makes pretty much their entire DAC, except for some very simple locally obtained parts in England. Plus they are incredible how they keep spare parts for so many years (so this is my understanding right now about their making their own dacs completely)
We upgraded to the MC462, and I’m going to see how the Bartok sounds as a preamp today (assuming I can as with the Rossini) without the C2600.. Doing and ABA kinda test, maybe ABAB... ;)
Actually, I think I'm gonna wait a few days for the breakin of the clock, so next week sometime I'll share the compare.