Maybe you can explain what audio issues you're having, and what you've tried, it seems
azalia(4) devices are configured in all sorts of exotic ways.. you may have to play with mixerctl to configure it properly.
If you were perhaps pointing out the failed attachment, that's for ATI's HDMI port, and it's unsupported by OpenBSD on all machines currently (..audio passthrough anyway, video unknown).
Here is your sound card, and it appears to be at least attaching properly:
azalia1 at pci0 dev 20 function 2 "ATI SBx00 HD Audio" rev 0x00: apic 4 int 16 (irq 4)
azalia1: codecs: IDT 92HD75B3/4
audio0 at azalia1
Good luck, and nice system.. memory over > 4G is not yet supported, although is a toggle in the source if you like playing with fire.