I haven't written any software in that vein, but from what I've heard, my first guess is that yeah, you could do it entirely within Hijack. I'm pretty sure the kernel knows when the DSP has switched to the Aux input. I'll bet a Hijack patch is going to be the simplest option. Mark still accepts patches to Hijack. You could activate/deactivate the functionality, and control its options, with the Empeg's CONFIG.INI file easily. That way it could be a permanent patch to Hijack that lies dormant and only takes effect when the proper configuration entries are set up.

I love this idea. If you code it to a specific popular module that's relatively inexpensive, this would be a great way to control the audio stream coming from the smartphone in your pocket without having to dig it out and fiddle with the buttons. Which module is this? And will your typical Android or iOS device respond to AVRCP?

If you successfully implemented this, I'd definitely buy the same bluetooth module and replace my current one with it. It'd be a direct plug in replacement, I'd just have to wire up the serial connection.

One of my typical use-cases is having my phone streaming Pandora bluetooth to the Empeg's aux-in while the screen of the smartphone is showing Waze. The problem is that if I want to skip to the next Pandora song, I have to task-switch out of Waze or do similar fiddling with the iphone screen to bring up its playback controls. This is far to fiddly to do safely while driving. Whereas if I could just reach down and press Next on the Empeg. This would be brilliant if you could make it work.