USB Extenders - Have Cat 5 Ethernet cable in between

ST Fiber optic Extenders - As for USB, but uses ST Fiber cables

Both these will give you 192/24 or even higher, of these USB extender using Cat 5 is cheapest and works.

I haven't tried this software, maybe this would do the trick?

http://www.net-usb.com/

am unsure of 480MB/s devices, why not download to try?

The USB input on the M51 is pretty good. After a while I came to the conclusion, however, that a good SPDIF source is better. The Squeezebox Touch used with the optical output is surprisingly good if you've never used one. It's probably the cheapest way and has a great user interface. It will only go to 96khz, however.

That any good USB cable preferably a good quality one.