A good hub should not affect the signal. If it does you will know it. Large blocky artifacts and other bad stuff will happen, and you would have to capture twice if you wanted to capture your audio through the mixer. Once for the audio once for the video. In the way that the previous poster said. I would use the fire wire port on that mixer if you do it this way just to have one less A/D conversion. Although you would probably be better off capturing just through the fire wire port. At work we capture DVCAM through a mixer but we use a analog capture board. That is the only efficient way to capture through a mixer.
