MSB DAC, or internal DAC in Sunfire?

Just spoke with Sunfire technical support and got the real deal on this issue. Will email Hotrod and Mhubbard. If anyone else wants to know please email me.

i have a sunfire 2 use a msb dac3 with upsampling with my sony9000es on cds sounds better than my levinson 39cd, hook up to cd analog input on sunfire, does not go through the da in sunfire.

If you use the external DAC you'll have some interesting hookup problems. The sunfire doesn't have a real analog pass-through (at least my 8 month old model does not), so you'll have to route the signal through another preamp. If you use the standard inputs on the sunfire, it goes A to D and then D to A, so you're using the DAC in the sunfire anyway. There is a way to use the 6-channel input on the sunfire as an analog pass-through, which has some disadvantages. If you want to know details send me some email (I'm actually using it that way currently).
Speaking stricly in terms of the quality of the DAC, I'm not familiar with your outboard DAC, but I can say that when I compared my theatre grand II's DACs with the DACs in a high quality CD player (e.g. CAL CL2500, $2500), the sunfire DACs didn't quite cut the mustard, although they weren't bad. Good luck.