USB treats devices like a hard drive. The computer takes the information as fast as it can. The protocol handling is often handed off to the host computer in the USB driver as well. So a USB device can potentially
create data bottlenecks and CPU drag. This can lead to drop-outs, glitches, and unexpected halts. Not saying it will but it can, especially at high track counts.
"Firewire" treats everything as a network device. The throughput protocol is handled by the firewire chip itself and each data stream has a bit rate attached to it. So a firewire stream has reserved bandwidth on the the I/O buss. There are no unexpected dropouts or glitches and the CPU is unaffected. You reach a maximum buss data saturation and that is the end. It just doesn't go beyond that.
USB2 vs. Firewire? USB can do a single data stream faster but it's theoretically
easier for a computer to handle high track counts with firewire... All things being equal, anyway. It clearly depends on the manufacturer's hardware and drivers -never mind that there are a gajillion USB chip manufacturers of varying quality and only a few Firewire chip makers and "we" know which ones to look out for. It's likely that you can hook two Fireface 800s to one firewire port and get ~100 channels of I/O AND
I don't think USB could handle that without hiccupping. BUT, both can handle ~50 or more 48/24 tracks in one direction so... what do you really need? In the end
, both protocols are just translating to the PCI buss... and that is exactly what TBolt is like: a direct connection to the PCI buss.
This is why TBolt is awesome. It's a reserved bandwidth high speed buss with a direct connection to the motherboard's southbridge, without an intermediary translation step like USB or Firewire. Instant lower latency!!! (although future TB cables with processing on them to go to optical
and back will probably add some latency). SO
if you connected a UAD PCIe card into the end of a TBolt (with a sonnet echo express or whatever) on a MacBook Pro then you have the same result as plugging on into the internal slot of a big azz tower machine.
The concept of having PT HD cards in an expansion chassis is pretty damn appealing.