this is a expensive box and solution though.
For what it does it is a bargain. And to take load off the machine it is a godsend.
Does the Teradek not accept audio via HDMI? In other words, do you have to use the 1/8" connector for audio?
Yes, the Teradek accepts audio via HDMI so if your Mac and Adapter support the Mini Displayport as an Audio device, you don't need the audio cable.
How about using one or more Cubes as video sources for BoinxTV, is that possible?