Do you use 1/4" cables and strip one end?
Could you use a Behringer ada8000 getting Toslink from a macbook pro? This would be a super cheap solution, if so.
Hey, a DIY question. It's been a while.
Yes I used 1/4" cables in my prototype, with only the + attached to the plates. The most important thing is length, the shorter the better. If you can take apart the interface and put it in a box with the sensor, that would be best.
As to interface I'm pretty sure any cheap one should work fine. You can look at what the G-Tar guys did in their forum post.
I don't think that the MacBook Pro supports 8-channel ADAT on its TOSLINK I/O. The ADA8000 probably doesn't support standard stereo digital audio over TOSLINK, either. In other words, they don't speak the same language.
Give it a try if you have the opportunity, but I have a hunch it won't work without writing some kind of serious driver for the MBP. I would not recommend buying the ADA8000 if you want it to do this, at least not without testing first.
There are many audio interfaces which have ADAT, but most either have 8 analog I/O or cost as much as 8 analog I/O.