Anyone connecting between a MAC and a DAC via optical?

Seems like a good way to remove any USB cable effects (if there are any, lets not debate that here please).

I'm interested in how this works, good, bad indifferent.

If there are any caveats, like file resolution limitations, etc.

What the limitations on cable length are, and or any other things like this.

Where's a good source for buying such a cable in decent lengths.

If you want to get very specific, I have a MBP mid-2009 and a V-DACII.

Thanks in advance for any/all input!