As the title suggests, I cannot get any sound output from a TV plugged into the HDMI port of my RX580 gfx card. The machine is dual boot with Win7 which is working fine, so i know it's not a hardware issue. I'm pretty sure the TV is connected to the 4th port (pcm3) on the gfx card, so I have tried changing the 
Not sure where to go from here as there is nothing obvious wrong with the setup.. any suggestions appreciated!
hw.snd.default_unit
to each available number (0..5) and then trying cat /dev/urandom > /dev/dsp
, but I hear nothing from any unit. I've also checked mixer volumes are set to 100, and speakers are turned way UP! 
Not sure where to go from here as there is nothing obvious wrong with the setup.. any suggestions appreciated!