Thanks! I installed the drivers on my Windows 10 system, making the FX100 a sound output device (via USB) and now I can play along with youtube and my own mp3s without any lag. I have connected the 2 "main out" lines to an old Yamaha AV receiver and drive either large speakers or headphones from there.
Cables required:
* USB 2.0 Cable - A-Male to B-Male (I have also used a USB 2.0 extenstion cable to lengthen the reach, but it is better to have a single cable.)
* shielded audio cable, male 1/4 inch mono to male RCA plug (left channel from "main out" on FX100.)
* shielded audio cable, male 1/4 inch mono to male RCA plug (right channel from "main out" on FX100.)
Instead of the separate output cables, you could use the stereo headphone jack with a TRS plug on one end of the cable to a pair of RCA plugs on the other end.