+t for the choice of 391's... that would work, but you have to make sure you computer's audio card has digital coax in's, then you just connect your coax out from your 7pin, i beleive.. someone with a d8 could tell you for sure, but it doens't seem hard. and the samson mixpad gives phantom power, so it would work, you could skip it and get a pre, will cost a bit more. but, spend it if you can... but you won't have an A/D and will just run analog in i take.. but you need a 7 pin cable to digitally transfer.. good luck.
matt