I have a Mackie Onyx 820i mixer with a FireWire interface that I connected to my iMac. I can plug my guitar in and play through it just fine (using Logic Pro). I can play youtube videos in browsers, etc. The problem I have is when I try to do both at the same time, the audio through FireWire (my guitar), is distorted. For example, I can watch a quicktime movie, then start playing guitar, and the audio is just all messed up.
Is there anything I can do to fix this? I updated the firmware on my Onyx. I just upgraded to Lion, and while this issue only sometimes happened before, it happens all of the time now since the Lion upgrade.