Never tried it, but assume you connect to the fixed output of 600i to high input of subs. Let me know how it sounds. Thought about doing it myself. I have the 300d v.1 DAC. You can get the version for cheaper since it only upsamples to 94. Look at my virtual system for details. Honestly, the 300 and 100 simaudio sounds the same. 300 have xlr output, which is only difference. I listen to mostly vinyl, so I did not splurge on the DAC. How does it sound, ok, I guess.