I've had a FireBox for about 9 years and use it a few times a week. I plugged in tonight and couldn't get any sound. After some troubleshooting, I realized that if I plugged in with XLR that I got a signal, but if I plugged in with a 1/4" I would not. But if I plug into inputs 3 and 4 in the back, it works (though it's much quieter...I need to figure out how to make them louder). My work around for tonight was using a bass DI, though oddly the signal is quieter than going straight in.
I tried various cables, and tried them in other settings to make sure the cables were good (they were). I tried various recording softwares (Reason, JamKazam). In both cases I got the same result.
Has the 1/4" portion of my main inputs just died? If so, is that easy to replace?