Hey, I've had this problem for days and I cannot find a fix for it. One of the two High Definition Audio Drivers is showing an exclamation mark over it in the Device Manger, and this now means that I cannot get audio over HDMI, which is a big issue for me, as I mainly use my SP3 when connected to a TV. HDMI inputs aren't even recognised in the playback options. This problem happened the other day, when I tried to start my Surface and it got stuck on the Surface Logo. I had to wait for the battery to die (holding the power button did not fix the issue), before plugging it in, at which point it booted. Since then, this issue has been here. I believe it is a firmware issue. I've tried the Realtek drivers, the Official SP3 drivers and tried reinstalling my whole system, the problem persists. Any suggestions would really be appreciated.