U2711, how to disable audio support?

My Dell U2711 monitor on DisplayPort connection is competing for audio resources with my Onkyo TX-SR308 AV receiver.

This led to very annoying times when I do not turn on my AV receiver before my monitor, leading to my sound device (AMD HD audio) switching to DP audio rather than HDMI audio. Only a system restart can I have my audio back. There is no way of switching the audio path between HDMI and DP. This has plagued me over 1 year and no one from AMD, despite repeated technical support queries, could help me.

I have tried EDID editing and removed the EDID information on audio support without luck.

Note that I cannot change my DP to DVI due to availability of ports on my video card, nor I can drive my monitor from HDMI, as U2711 is incapable of supporting HDMI with native resolution of 2560x1440. Attempt to use DP to DVI converters also fail as most of them, even active converters, do not support DP to dual-link DVI at 2560x1440 resolutions.