fglrx - playing music via HDMI with disabled LVDS

I'm using MPD (Music Player Daemon) and its "Best Sinc Interpolator" on Debian GNU/Linux laptop as my source of HD sound for my Marantz PM-80 stereo amplifier. It's connected via digital HDMI interface converted to analog RCA via HDMI converter (DAC). In the future I plan to replace RCA outputs with toslink (SPDIF) connected to some robust vintage DAC with RCA otputs.

With this setup I had one issue. fglrx the proprietary graphic driver by AMD was disabling HDMI interface upon DPMS activation. This disables the audio also. The simple solution is to disable DPMS, but wait, it's laptop and I want to have LVDS display turned off when I am using it only as source of audio at the time. With open source radeon driver you can propably use radeon.audio=1. This is not the case with fglrx and I decided to start switching LVDS off with shortcuts managed xrandr.

I'm using XMonad as my window manager so I added following entries to my keymap.

 
	,("M-d", spawn "/usr/bin/xrandr --output LVDS --auto && /usr/bin/xset +dpms")
	,("M-S-d", spawn "/usr/bin/xrandr --output LVDS --off && /usr/bin/xset -dpms")
 

The first keys combination, in my case Win+d enables LVDS output and DPMS features.
The second keys combionation, Win+Shift+d disables LVDS output and also DPMS features.

So, with this solution the display is off and HDMI output can't be interrupted nor disabled because of DPMS energy saving features. When I want to work with this laptop I simply press WinKey+d to enable its display. In this case DPMS is needed when I am away from keyboard to save energy and display itself.