Preamp and DAC combination for upgrade

issue: wondering if I can get a single unit preamp/dac as part of upgrading 2 channel listening. And, if so, what are some good options.

I currently have the following system:
NAD T765 A/V receiver
Quad 12L2s (Front L/R) with Quad Center and mini monitors for surround (MIT cables)
REL Sub
Sony blue ray and HD cable box and sonos

I would like to improve two channel listening by purchasing new amps (looking at Bel Canto, Wyred or NuForce mono blocks) and dedicated, higher quality CD player.

Goal would be to have:
1) the 2 channel system for listening (cd and sonos source through "pre/DAC" to mono blocks driving 12L2's and REL;
2) 5.1 channel for movies and TV (NAD 765 serving as processor for dvd, cable and driving center and rear speakers with a line level pre out to new pre/pro so 12L2's and REL in "2 channel set-up" will be the Front L/R and sub when needed for 5.1 system.

My question is if there a preamp/dac combination that would work (instead of buying separate preamp (for pass through from NAD for 5.1) and DAC to get quality sound out of the digital sources).

Thanks for any help/insights