Hi, just wondering if you ever found a solution or was this a hardware defect? I just got an Audiobox USB 96 and I am experiencing the exact issue--the gain knobs on input 1 and 2 do not affect the gain at all. Does not lower it, nor does not increase it. It *was* working for like 15 minutes when I first set it up--but then inexplicably stopped working.
**Never mind, it turns out at some point I started using the gain control knob #1 with input 2 and vice versa!