Bryston SP1.7 Bypass or Digital In ????

I am looking to purchase the Bryston SP 1.7 pre-processor and was wondering a few thing about the 2 channel bypass-vs-using the digital in. As of now I am using the BP20 Pre. I guess my question would be how well does the processor work as a DAC when I send a digital signal into as apposed to an analog one. As of now I am using a Krell Studio as a DAC. It should be a upgrade to that but I plain to replace my current transport with either the new Krell showcase DVD to rid myself of having both a transport and a DVD player, or if that does not work maybe the 280CD. Is the DAC in the SP 1.7 going to be better then using the analog outs of those players.

How good is the DAC ???, will I be happy using it or should I look to a player or DAC and use the bypass ??? How much of a issue is it that the analog is RCA in only and no XLR ???

Thanks in advance,

Pete