I am doing almost the same as Sidssp, but I run an iMac into a non-USB Benchmark. This means using the optical out from the Mac. This is a mini-optical, you can either use a converter or buy a cable that has mini-optical in one end and regular Toslink in the other (I bought a Monster for about 50 bucks, I though that it would be best to avoid an extra glass surface transfer). You are in business if your DAC has an unused Toslink input!
The comments about being careful about the transfer rates to avoid any conversion that reduces the sampling frequency still apply (most people says that it is OK for iTunes to upsample to 96k).
The comments about being careful about the transfer rates to avoid any conversion that reduces the sampling frequency still apply (most people says that it is OK for iTunes to upsample to 96k).