Maximum USB Cable Length
The max cable length MOTU recommends between a USB computer and USB interface is 5 meters (16.5 feet). Longer runs can be achieved thru the use of POWERED USB HUBS. For extremely long runs, MOTU has tested the device USB CAT5 EXTENDER referenced in the link below.
This allows USB runs of up to 100 feet!
http://www.nti1.com/usbc5.html