To be honest Csyckad ESXi 5.0 is a better bet if you want to do passthrough. It has working USB where 5.1 dosent. HDMI audio is normaly going to be driver related. You can attempted to lower the audio quality in Windows and see if that helps but I have little hopes for that... Need a tab more background on your VM setup to find the cause.
There is very little difference between 5.0 and 5.1 for a home lab unless your actually using DRS... In that case I opt to eat my own words lol.