Bit late posting this on here but last week I finished installing a mod on a DMG with a bluetooth audio transmitter.
Demo video here: https://youtu.be/StovYnUdeq8
Article here: http://www.nintendolife.com/news/2015/0 … e_heck_not
It's the first time I've tried it as a Gameboy mod and as far as I can tell it's the first internal bluetooth transmitter on a DMG. I had to figure it out as I went along, part planning, part trial and error. The end result works really well although there is a slight lag in the audio. Next time I do one I'll try and get a transmitter module that's a bit more instant. Also, I'm using the select button to operate it and there have been a few people voicing concerns about this messing up LSDJ as it makes a lot of use of the select button. The mod could easily be done with a momentary switch instead but I quite fancied hacking the select button. It only operates the bluetooth when held for 3 or 5 seconds and hasn't caused me any problems so far.
Pretty pleased with how it turned out and makes a nice change from the usual mods. Once I get the hang of it I'll put a tutorial together if there's interest.