Suggest calling Audio Research. If anyone knew, they would. In my experience they are usually happy to help with these types of questions. I own the DAC7 but not the CD3 MKII. Looking at the specs for the CD3 MKII, that unit looks pretty substantial, and I doubt the DAC7 would be the significant upgrade you are looking for. With digital the law of diminishing returns sets in fast and I think it would take a lot of $ to better the CD3 MKII in any meaningful way.
change to ARC Dac 7?
Would changing my ARC CD 3 Mk 2 with the addition of an ARC Dac 7 be a worth while upgrade? Would I be gaining just an incremental benefit or would it be a large enough benefit in resoulution,sound staging, and overall responce to warrent that type of change or would I be better off looking in a different part of my system if I were to make any change? If you've done this change your opinin would be very welcome as to the differences you've experienced. Thanks in advance