Question

When using my Audiobox USB, does it matter which channel (1 or 2) that I use for an instrument 1/4" jack or XLR mic cable?  Both channels are equipped to accept either one.  Or is one channel preferred over another?  In the previous answer, the comment seems to imply that Channel One is for connecting an instrument.

Answer 1

Either works fine. Which you choose is up to your personal preference.

Or you could hook up 2 guitars and record one on one track and the other on another track

if you want to record yourself and a friend at the same time.

You'd just need to get a Y splitter for the headphones.