Just as a follow-up: I find myself astounded at the sound quality of my G4 laptop out to the Waveterminal U24 into the preamp section of my 6900 integrated. I preferred the sound of this combo to the Apogee Mini-DAC (used both as a stand alone DAC and direct drive into amp). Don't get me wrong, the Apogee was excellent and I learned a lot from it, but it was not a significant enough improvement over the Waveterminal set-up to justify the 1K price-tag (I got the Apogee from Sweetwater, they are a GREAT dealer and had a 30-day money back guarantee). It was mostly different.
I am now auditioning the Benchmark Dac-1. Too early to say but I will follow up once I have logged some hours with it both stand alone and direct drive into my amp section of the 6900.
It has been fun!