Great thread. I eventually got sick of component on my 16:10 display because I could either go with black bars, or a weighted zoom which cropped a bit off each side. I knew connecting through HDMI would allow me full stretch even if the aspect was off a bit. I didn't care since I played a bunch of PS3 games and it didn't bother me, but the cropping did.
So I found a cheap $6 china knock off audio adapter and figured why not. Not surprisingly it worked and it didn't. RCA audio worked, but no HDMI video and no Toslink light so I knew the console thought it was component or VGA or whatever. Started looking around for circuit diagrams and what pins did what and found your really simple fix.
Wonder if I should look around if anyone has found my fix about how a simple jumper wire is all you need to keep controllers from thinking a headset is plugged in and locking out wireless mics from that quadrant without losing any functionality. I see like ten a week on the official forums and I should create one or find a link to send them to.
If you want to find the adapter I found for cheap it's model to google is
Microsoft X808221-001 Xbox 360 RCA Audio Adapter
Got it off buy now ebay front for $6 so can't beat that and this solder job will fix it right up.