Theoretically, yes. n-Track will allow you to select multiple drivers.
Realistically, no. I mean, yeah, you may be able to get 8 channels of audio in ... but you'll have no way of syncing the two cards to a common clock. Other than the computers system clock, which is totally un-reliable for audio work.
You would likely have better luck if you have the S/PDIF option card for the Gadget and a Delta 66. Then you could sync the two via S/PDIF. Provided that the control panels for each card offers the ability to send/receive clock signal via S/PDIF.
The best bet would be the ADAT Lightpipe option card for the Gadget and any one of the numerous ADAT front-ends.
