I tested this interface for a while (took it from Guitar Center and then returned it after a couple of days) - there seems to be a constant low-level background noise when you record through the preamps. Could someone who uses Firestudio Mobile confirm that problem? Or was it maybe just a faulty unit? I don't want to spend any money before making sure it's not a frequent problem with these interfaces.

What did you have plugged into it testing ??

I had a Firepod which was a bit noisy with unbalanced stuff, till I put things through a DI first.

I can't vouch for your Firestudio, but I had a Firebox with terribly noisy mic preamps (and crosstalk between channels). The warranty replacement was the same.

Thanks! I think I prefer a Focusrite Saffire.