Jeff, in my view the problem is the replacement of the AV receiver that you're presently using as a pre/pro. Is there actually a good reason for doing so? As far as the relative DAC possibilities, Alan, among others, has emphasized that DACs are a mature technology and aren't audibly distinguishable although of course small measurable differences still exist. So the answer is no, you don't need an external DAC(also keep in mind that you might be paying more for hot air rather than "quality"in the DACs that you've mentioned).
