When I look at the MOB's spec sheet, I see that whereas it can be set to 44.1khz or 48khz, it does not show any other resolution than 24 bit.
See:
http://www.mackie.com/Products/onyxblackjack/pdf/Blackjack_SS.pdf
However, I can't see that the interface is needed with Rocksmith. My understanding is that Rocksmith uses a 6.5mm jack to USB converter. So you go
straight from guitar to PC.
See:
'Rocksmith requires a unique quarter-inch to USB cable that allows users to plug any real guitar with a quarter-inch jack directly into their Xbox 360, PlayStation 3, PC, or Mac. Developed exclusively for Rocksmith, this revolutionary cable turns the guitar’s signal from analog to digital, allowing it to be recognized and played through your hardware device. Rocksmith is bundled with the required cable, except in download versions and the Rocksmith 2014
Edition "No Cable Included" Version'