Matt, Thank you, thank you, thank you for bringing this device to my attention. I was looking for something like this for a while now. Well, not actively looking, but thinking "something like this must surely exist?". The only things I could come up with so far were battery powered, and I don't want those. This device seems to fit the bill perfectly. I'm using an iPhone, so hopefully that AVRCP issue you're mentioning won't bother me as much.

Edit: bought one on Amazon.