You could try just getting some bluetooth headphones like this and modify those to fit in your helmet. I did it recently with some $20 headphones and some yarn, they turned out really well and I get nice crisp sound (also the buttons are big enough to feel for controls). Took maybe a afternoon to cut all the plastic off and wrap it.
All I need to do is test how long the battery lasts in the cold....
On Amazon, the Kinivo BTH240 Bluetooth Stereo Headphone seems like it might do the trick.
Really good reviews, though nothing amazing (they're only $30, after all).
Let us know if you find something that plugs in, too.
