If you own a computer with Firewire output and want a low cost high quality way to convert to S/PDIF digital cable this is your ticket. I used this unit between my Mac Mini and my high end DAC with great results. Turns out it's clean, clear, and seems to be absent the timing errors that are present in USB outputs.
It also works without A.C. power (passive) meaning no added A.C. noise. (Because I did not use the wall wart power supply, I promptly lost it. So it does not come with power cord. On Ebay they are about $6.00. Do a Google search for all your other options in using this versatile piece.
There are many of these on Ebay - mostly for use by musicians. I prefer to sell on Audiogon.
I will ship with UPS. Buyer pays shipping. Paypal is fine.