Modding AC97 Front Panel Cases to HD Audio?

[zombielando]

I recently bought a lot of computer cases and most were AC97 Front Panel audio. While they work with HD Audio motherboards when you disable front panel detection, the rear speakers cannot mute when you plug headphones into the front panel so you end up with audio coming from the headphones and rear speakers.

Does anyone know of a cheap mod case mod to allow for muting of the rear speakers when you plug in headphones into the front panel AC97 audio jack?

I found this http://www.moddiy.com/products/USB{47}AC97{47}HD%2dAudio-Motherboard-Internal-Front-Panel-Cable.html which claims to support HD Audio but it only has one "audio plug" and every case I've ever dealt with that had AC97 or HD Audio support had both cables (AC97 and HD Audio) cable. It'd be awesome if it was HD Audio as it looks identical to the cases front panel card except it has two usb (the cases only have one usb port so that's not an issue).

I messaged the company but have not gotten a response yet so I'm wondering if anyone here has had any experience in doing anything like this before I buy one for testing purposes.

Thanks.