DAC for Olive musica

The opus is without a doubt a better machine, but the price is much higher as well. I plan on using the musica with a $500-750 preowned DAC for as good, I hope, results.

I see ...and thats a good plan IMO. You get more bang for your buck on the used market, and if the DAC doesnt suit you, or if you want to upgrade, it wont be very difficult or costly.

If you want a DIY DAC a good choice is the Rakk Dac from K&K Audio. I am currently using one with a Musica with Great results. http://www.kandkaudio.com/
I am also using one with the DEQX 2.6p which is a little more than a DAC but I am getting good results from it as well.

I know it's been discussed before, but how about the benchmark vs. the audio mirror. They are very different animals, but for my use with the olive which is preferred. I doubt the olive will have the finest transport mechanism so are upsampling and jitter control an important issue?

The point of the transport on the Olive is to make a copy of your CD onto the hard drive, not to play CDs directly from the transport. Using hard drive, in theory, is much better than a CD transport in terms of noise. HD proponents claim that it is better than any CD transport out there, no matter the cost. For us that's the most important aspect of HD based music servers, besides the unbridled convenience of accessing all of your CD collection in a matter of seconds. Long as your DAC has a USB connection, you can play directly from the HD. "That's all I have to say about that." - Forest Gump.