2in/2out a plug into the USB port on the computer. This is the minimum and have 2in 2out
Required to use his laptop in an audio setup (in my opinion)
I use it with an expander mk249c ts and the two branches of the Edirol.

UTILIZATION

For drivers, I know, I've download on the site for my edirol xp
otherwise it comes with drivers on CD (I do not know where I not open the cd)
it works with cubase everything is nickel

OVERALL OPINION

I use it for months qq
I was afraid it was too big but it's going good actually.
I got down on other reviews for the choice and I think it's a good choice trs
report quality price relation that exists is good relativmeent (100 € -120 €)
Exprience I would do with this choice, really Do not hesitate and especially AVOID (except in exceptional cases) the 1in/1out.