Nvidia +Hdmi = problems?

Right i have a weird problem, basically i had my system setup like so:
gpu --hdmi--> av receiver(pioneer vsx-520)---hdmi/dvi--> monitor, worked ok but one major problem was that somehow my av receiver was doing something where it made my monitor bright, blacks were no longer blacks more like grey even on 0 brightness (compared to almost black on 0 with a straight connection to monitor), it was intolerable and i think ive narrowed it down to my av receiver (no way to sort out via settings afaik).

Basically i decided to just go dvi--> dvi from gpu to monitor, however i want my sound going to my speakers (to my av...), my idea was to connect the HDMI cable to my av receiver and just use the audio over that but it seems its not so simple? It works BUT only when i have the graphics output setting a dual monitor mode, aka using my av receiver as a display and my main monitor (a fake dual screen as the vsx isnt a monitor...) so audio works like that but as soon as i disable dual screen it doesnt work and the windows 7 audio panel changes from "nvidia hight definition audio connected" to "nvidia high definition audio cable unplugged", i dont get why i cant just pass audio over hdmi without having to run dual screen? also using dual screen seems to give me a millisecond black box every minute or so, annoying :(.

Any helps appreciated as its SO annoying

mmm HDCP related perhaps?

What you have is the only solution if your amp is messing with the PQ.

I use Ultramon to "disable" the second desktop.

The problem is that the DVI or HDMI port is not active until windows uses it as part of the desktop......

hdcp isnt a problem, monitor supports it and so does everything else. I tried using that ultramon but it didnt like me setting my monitor as the proper main display so it wouldnt work(kept reverting back after applying..)

Will have to dig deeper, must be something ive missed.

I've never had to set a main display in ultramon, I just tell it to ignore the desktop that the amp is displaying...."tick ignore monitor" and "ignore enabled monitor".