When I turn off and back on my receiver, the HDMI out of the AMD video card shuts down, and doesn't turn on again until I open Sound in the Winblows control panel. Then it appears as not plugged in with the little red x, which turns green in about 1-2 seconds. Then I can close the sound options. MC automatically sees the HDMI and switches to it (if I've selected the zone that uses the HDMI out), so I don't have to do anything in MC's options.
Leaving the main zone on my receiver on at all times would solve the problem, I guess, but there's enough heat generated in my AV cabinet already.
I might have to get me one of those HDMI Detectives too! Too bad they're double the price here in Norway...