Have you thought about getting Bluetooth system for your helmet?
For the longest time I have refused to go with a external Bluetooth module which attached to helmet with speakers & mic tapped to inside the helmet for one reason which is if I decide to change my helmet I have to remove all that and mount to a different helmet. What a pain in the rear......so I bought LG Tone Ultra Bluetooth headset and was happy with it, great sound system then when I got my SG I thought I can pair to the system and was very disappointed to find out no such luck. Going wired will be the same as Bluetooth setup where I will have to remove inside helmet speakers & mic when I change around helmets.
But I bought a Bluetooth modules for wife & I to communicate when we go on longer rides, just got it and have not actually tested it but just playing around with them at home I am impressed. Wife can listen to her own music through the Bluetooth module from her helmet as I do with my own music through mine then when we need to talk to each other just press a button and we are communicating. And most of all GPS will override music so that's a good thing.....
There are several make & models out there...