I can't seem to find any questions about this. I'm just wondering what I can plug into the Aux Input on my POD HD. The manual just says a second guitar or pretty much any instrument but doesn't list examples. I just wanted to make sure if I can plug in a keyboard, electronic drums, or the line out of an amp for recording since this is my only interface. Can I use the Aux in like the Line in that I had on my POD Studio UX2?