I have the Blue Circle USB Thingee up and running. I am running off the headphone jack into my preamp.
Initial impression is awesome for the money I spent. A lot of dynamaic range, really clean bass. I have not begun the A/B/C testing yet.
I can understand why UHF mag ran it into another DAC, to get more gain out of the unit. It runs fine in stand-alone mode though.
I got a gold palted 3ft USB cable (from the Shack) to go from the puter to the Thingee. I'll replace the headphone cable later on, or switch to the RCA jacks.
Make sure you set all your volumes in the system settings on your PC to the max.
It truly is ALL in the music!