The USB connection on an original 01V96 (and the 01V96VCM) does not transfer any audio. It's used for MIDI and other sequencing and control tasks, and also for the control surface interface. By contrast, the new 01V96i can transfer up to 16 channels of audio via its USB connection, but, as far as I know, this capability is not retro-fittable to older 01V96s.

With these older 01V96s, you transfer digital audio data using ADAT lightpipes. Each ADAT port can send 8 channels of audio at standard rates (44.1 or 48KHz), and half that number at double sampling rates. The 01V96 is supplied with one ADAT port in each direction on the main chassis, and to get more you need to plug a MY16-AT expansion board into the expansion slot (don't bother with the MY8-AT board) to give you a total of 3 ADAT ports in each direction = 24 channels each way at the standard sampling rates.

You can set up the computer end in two main ways: internal boards or external equipment.

For a board in your computer, you will need one that has at least two ADAT input ports if you want 16 channels. Something like a Marian Seraph A3 board would be suitable if you have a desktop computer with serial PCIe slots. There are other boards for the parallel PCI bus, and also ExpressCards available with a similar function if you have a laptop.

For external equipment, there are two main FireWire-interfaced units to look at: the Presonus FireStudio Lightpipe (discontinued but still available) and the M-Audio Profire Lightbridge. Both of these have 4 ADAT ports.