Disabling HDMI sound

Hi All,

My new machine has an ASUS motherboard:

H170M-E D3


and an AMD Radeon R7 360 video card.


I'm running Kubuntu 14.04


I am getting no sound through the motherboard's onboard sound card.

I get sound over HDMI and fortunately my monitor has an HDMI port AND
built in speakers. However these are no-where near as good as my
desktop speakers.

The only option in the BIOS is HD Audio Controller (enable/disable).
However nothing I change here has any effect.

In the GUI the onboard sound is greyed out. Alsamixer shows HDMI sound
only. The desktop GUI shows only HDMI.

aplay -l shows only the HDMI sound.

I have tried a number of things including
/etc/modprobe.d/blacklist I have added

snd_hda_intel

and adding a line in GRUB
radeon.audio=1 and using 0 as well.

I have found another possible solution here:
http://xorg.freedesktop.org/wiki/RadeonFeature/

Which suggests, under Linux kernel parameters

Option: radeon.audio
Value:: 0,1
Default Value: 0
Explanation: Disable/enable HDMI audio

My question is: what *do* I do with this? I'm assuming I need to
add/remove something *somwhere* but...where/what?

Any help would be most appreciated. Without the onboard sound card I'm
stuck with the crappy monitor speakers and cannot use headphones nor
use a microphone for video conferencing etc.

Regards,

Patrick