Steve, yes, you can go through the mixer first, then the preamp. And, you need to run the line out from the preamp to the mic jack on the soundcard. I've found by trying to play CD's over Paltalk that the line-in doesn't produce enough volume.

BTW, I was in the room when you first performed on Paltalk and I was able to hear you, although, as you say, your volume level is low. I had to turn my sound all the way up for you, whereas for most performers I have it set at about 30%.

As far as the mono to stereo connection goes, I have my mono mic plug going directly into my stereo jack with no converter, and it works fine. But, as I remember, before I used a preamp, I had to fiddle with the plug in the jack to get enough volume. Seems like I ended up with it pulled partway out.