[John Jordan]

Having owned a C 2500 for about 4 years, there were initial problems with the USB locking up the DAC. No problem was ever experienced when using just the Toslink or COAX inputs. The USB problems now seem to be solved. I feel the correction is attributed to:

1. upgrade of firmware to 1.03
2. changing from a 5 meter Belkin Gold cable to a 1 meter Straight Wyre (the one sold at the SchiitR for $20). Nothing super fancy!
3. an upgrade to Mac OS 10 last fall that had "better compatibility with third party audio devices improved" as one of the improvements.

Music is played though Amarra 4.0 luxe. When changing from USB to Toslink output on the computer, as per Amarra's suggestion:
Stop music/switch output in Amarra's device settings/change DAC input and hit play. Just going into device settings and changing the output for a fast A-B, will most certainly lock-up the DAC.

As far as cheap USB cables vs better cables, there have been documented problems of fancy cables not working properly with various set-ups. This was due to the fancy cable not being USB 2.0 compliant. So compliancy as well as length are factors. Also, some folks using devices in the USB chain to re-clock etc have found these devices interfere with DAC recognition. If trying, be sure that there is a return policy. Personally, I did try one such devise and ultimately returned it. It did very little and mostly nothing; some music was actually degraded.