I'll be going thru this thread for help and inspiration as I tackle an XBOX powered bartop project shortly. Like yourself I'm going with a KADE for the controlls.
Years ago I purchased 3 "altered" XBOX consoles on the cheap. They were running
LINUX. If I recall correct they were configured with LINUX as a school project.
(That is what the guy told me anyway)
They were cheap so I bought them! I had the chips flashed and installed XBMC and new larger hard drives @ my local "console chop shop."
When I bought them the guy included an adapter with a USB connection on the end. I never had a use for it til now. But I know this will work and easily allow me to use the KADE.
I have an extra RGB VGA adapter that I'll use in connection with a PC monitor.
I just need to find (buy) an extra XBOX component cable.
The only thing I need to solve is the audio and adding an external power button.
I'm looking forward to this.
Audio is easy just use a small kinter amp..
THE HD rgb cables for xbox have 2 rca cables for audio, plug these into the amp, and speaker wires to the speakers. It runs off the xbox 12v.
These covers are really nice and cheap for 3" speakers. Get them at 8-line supply.
The external power is easy to. Just wire a pushbutton to the power board. There are 4 solder points on the back of the xboxes power switchboard. Just solder to the 2 right points. Shown at 8:25 in the video.
Just follow degenetrons tutorials, you'll see them on youtube. all of your questions will get answered.
If you want your power button to be lit up before you even turn the unit on, i can show you how to do that in case you want to add that feature too.
Jammin0's rig is off the chain, I love it, i've built a few xbox powered bartops as well, they are fun.
Good luck