Assuming your Dac doesn't have a USB input get an USB to spdif converter. You run a USB out from your Mac to the converter and a digital coax cable to your Dac. Just google USB converter there are tons of them out there and various price points.
You must have a verified phone number and physical address in order to post in the Audiogon Forums. Please return to Audiogon.com and complete this step. If you have any questions please contact Support.