Audio on this board is good from the rear port but, the second I plug it into a front audio port (the cables to the front ports are not shielded) I get like a 1500hz tone with 1hz oscillation, with a lot of noise. Unfortunately the only way I see the ability to trigger the headphone amp is to go through the front audio port.
The annoying green audio LED trace can be shut off under "Audio LED" in the bios.
Also, mine came shipped with BIOS version F3. I saw there's a F5 out now, which when I installed it fixed a bunch of stability problems not being able to get over 4.2Ghz stable, fixed CPU temperature in the BIOS (was reading WAY too high). Classic BIOS aren't nearly as buggy as the Windows mode BIOS. I also noticed the CPU support list says all Haswell CPU's were only supported since version F5. Version F3 is more than a month older than F5. It comes shipped with F3.
If you're having any stability problems, I suggest upgrading to F5.