So I've been playing around with different configurations for the last couple days. Here's what I've found out.
1. I did find that by using the MME drivers I can get Guitar Rig 3 to recognize the JV as an input interface, and can get output through the sound card and the JV itself. But, Guitar Tracks Pro still doesn't pull any input from the JamVox at all. It doesn't matter which driver set I'm using.
The JV ASIO drivers aren't recognized by GR3, but are recognized by the JV software. I'm assuming that there is a proprietary hardware handshake in there that only the JV uses and makes the hardware unresponsive to other programs using the ASIO driver.
2. I discovered a problem with the Lexicon ASIO drivers by selecting it in GTP as the input device. Originally, I got nothing, just dead silence, no signal at all when I had the ASIO drivers selected. If I switched to the MME drivers for the Lexicon, I could get some very very weak signal that was totally masked by a very loud, persistent buzz. Nothing I did changed that.
After some research and hair pulling, I reinstalled the drivers for the Lexicon and for the JV. JV is back up and running fine, but when I try either of the Lexicon's drivers (ASIO or MME), I get the buzzing.
After even more research, it seems that this is a common problem with the Lexicon Omega, and many users have simply resorted to new USB interfaces to solve the problem. (One user even suggested Percussive Maintenance as a last resort by banging on the top of the thing until it either breaks or works. :dontknow
So, I changed the title of the thread to reflect my new search for a good USB interface that can take both mics and 1/4" TRS cables and doesn't need phantom power. I've seen the M-audio interfaces at the local GC and think that might be the way to go.
Any suggestions greatly appreciated.