So glad I happened across this discussion, and the similar one on the apple site. I set up my FF800 on both a Mac Pro and a MacBook Pro. I have zero problems on the MacPro and am running the most recent updates Firmware 1.77 and Driver 2.93. However, on the MacBook, the unit only functions with Drivers up until 2.75. Any attempt at installing an updated driver beyond that and the FF800 will not register a signal or send one to the speakers. It is recognised on the computer and the computer recognises it and the physical unit itself is recieving a signal (as LED's suggest) but the GUI does not suggest same. Interestingly, I run it via FW800 on the MacBook and FW400 on the MacPro. Installing 2.75 Driver again and all is great again. Both computers are running the same OS and I am using the same audio software to test. Both Apple and RME tell me that they have no idea what the problem could be. After much research, I now believe it is indeed a MacBook Chipset issue, but am at a loss to explain why this occurs to some users in earlier versions of the driver than has happened to me. Nonetheless, I am happy to run with 2.75 (Can't really notice anything different with updated drivers anyhow.) By the way, it still runs beautifully on the MacPro via FW800, so it is not a port issue from the FF.