I had the MS Advanced RGB Scard cable to the Xbox 360 to have on my Sharkoon X-Tatic Digital sound, which is good if you want to play at night.
However, I always had the problem that I switch my TV when ever NEN restart the Xbox 360 had, because the Scard cable and HDMI cables are not compatible at the same time.
This audio adapter solves this problem
it is even still NEN HDMI cable, but what I currently do not need.