Common symptom from what I've found searching the forums; Playing back 1920x1080 at 10-bit through the Kona, video plays back slowly (repeating frames a couple of times a second, lags behind audio almost instantly.) However, existing solutions haven't helped.
I've got the Kona LHe in a "2,1" Dual Quad 3Ghz Mac Pro. Kona was in Slot 3 set to 4X, but I've since moved it to Slot 4 set to 8X to no avail.
What I DID find, however, is that if I set the audio playback to "Default" rather than "KonaLH", it plays back perfectly.... even though the audio is still coming out the Kona, NOT the Mac's line out (and I checked, MacOS's normal system audio out is set to the built-in Line Out on the Mac.) Switch the audio playback back to KonaLH, and it's messed up again. It's 100% repeatable.
1. Why? :)
2. What is "default"?
8-bit works perfectly no matter what the settings.