The best setup for SCP and PTHD is as follows:
Pro Tools 7-9HD running on a mac pro osx 10.5/6
Hardware setup:
1- Optical out of the mac into an maudio C02.
http://www.m-audio.com/products/en_us/CO2.html
2- spdif/coax out of the maudio co2 in to a 75ohm to 110ohm balancing transformer.
http://www.markertek.com/Audio-Equip...hing-Transform er/Connectronics/AESEBU1.xhtml
3- AES out of the balancing transformer into one of the main 8 AES inputs on the 192.
4-Optical out of the 192 chassi (right side near the power plug) directly into the mac optical input.
software setup pt1:
1- Protools clocks to the internal or sync clock.
2- The mac should probably have an aggregated device made in out of the mac optical input and output.
3- The mac should lock to the signal it receives from its optical input and it should resample its optical output. (all setup in the applications/utilities/audio midi setup.
ProTools /Source-Connect software setup pt2:
1- Source-Connect sends its audio to and gets its audio from the mac's optical ports.
2- Protools should have it's 192 hardware setup with the chassi in optical spdif mode.
3- Setup a Source-Connect receive in the I/O setup from the corresponding AES input.
4- Setup a Source-Connect send in I/O setup from the 192 optical enc out.
5- In the session mixer don't send the Source-Connect receive to its send (setup a mix minus).
6- Also in the Pro Tools mixer create a mono audio track and put in the insert the rtas instrument serwire.
this should get around all the clocking issues. i don;t know why this works but send out one port (optical enc) on the 192 and receiving an another (AES) seems to work. its some strange issue between protools hardware and the newer macs.