Ah, 4-track recording — the Tascam 4-track tape machines could do it. But Mbox2 can’t support more than two tracks of simultaneous analog inputs at once (for mic / line / guitar ins, etc.) Is that a deal killer? Not at all; there are lots of people out there who use interfaces alone, adding a guitar or vocals but not much else at once. But if you do need more, here are a few of the interfaces in the Mbox2 price range that can:
M-Audio 1814 (which you can use with Pro Tools M-Powered if you must have Pro Tools)
PreSonus FireBox (which has a separate headphone cue — awesome)
MOTU 828, 828 mk. II, Traveler (slightly pricier, but much more I/O)
Edirol UA-101 (among other Edirol models) — 10 inputs for only a few dollars more! (Not sure about quality of the pres on the Edirol, though; haven’t used it.)
Many other’s don’t have more than 2 ins, of course — like the Focusrite Saffire, which is also 2-in only.
Don’t get me wrong — the Mbox2 can be a great deal with the included software bundle, which I think is the main selling point. But I notice many people don’t realize the Mbox has competition, like my colleagues over at Gizmodo.
Did I miss any interfaces in the price range that you love? I’m writing a roundup now, so I want to make sure I don’t miss anything.