This is a good interface, however, mine came with the 48v channel sending out 80v for some reason and I couldn't plug two 48v dependant devices without it starting to make noise.
You should have a powered usb hub for this interface just to be sure it receives all the juice it needs to function properly.
The audio quality is good, preamps are fairly quiet and it is really really well build.
if it wasn't for the fact that it came broken in the first place, I'd easily give it 4+ stars, however, seeing it as a recurrent problem online, I'm afraid I cannot.
The drivers sometimes bug and I'm left with no sound and have turn the interface on and off.
If you're planing to use this with a guitar, you should have a DI Box because with RG421's quantum pickups, on the lowest gain possible, it still clips slightly.
Overall, it's a worth considering interface, with great build and sound quality. However, i'd recommend you checking out a newer presonus one or a Focusrite interface if the price difference doesnt bother you. Look for one with a pad button if you plan to use a guitar.