Sure, the MF A5.5 would work as the DAC is built in with the pre, and the amp. Here is the manual which has extensive references to PC/MAC integration:
http://www.musicalfidelity.com/manuals/a55/a55int_eng.pdfNever heard the A5.5, but I own a good deal of MF equipment and enjoy the heck out of it daily.
BTW, I also have a SACD collection and while I do love the sound, I would not recommend starting a new collection as the format is dying. IMO you should look to the new Blu-ray HD formats. Or, just buy a good redbook CD player for now and wait until more BR audio titles are available and there are more BR hi-res audiophile quality CDPs to choose from. On the other hand, you may be able to pick up SACDs & players very inexpensively...