Volume control doesnt work when using HDMI -> AMP

Any ideas?

Before I had it set up to use analogue the volume control worked fine, press F10 and the volume goes up, press F9 and it goes down - you get the idea.

Anyway I now have HDMI -> Amp and when I try and change the volume through XBMC it displays the volume display on screen but doesnt respond to up or down.

Have I set something wrong?

I have tried changing the volume using the methods that worked previously - volume slider on keyboard, volume buttons on remote (set up using Intelliremote) and the F* keys on the keyboard - same result with all.

edit: sorry, should also mention I am using an AMD Radeon 5770 for HDMI output and I have tried wasapi and direct sound - same with both.

Do the volume controls work outside of XBMC, could be a windows issue.

Volume control doesn't work when you've got pass through enabled, you'll need to use your amps volume control.

Thank you for the replies. I see what you mean tungmeister, the volume control only works for 2 channel non ac3/dts files, so it works fine for mp3.