Not sure why folks get all excited about 'sound quality' on an open-air vehicle. Unless you're running in-ear buds, you're going to get some outside noise. Road noise, engine noise, wind noise, and if you're riding with HD's, exhaust noise. I don't care what sort of windshield you've got, you're getting noise. Frankly, the difference in what a bluetooth receiver gets you and a plug is academic and have other pros/cons (the tethering vice battery life concern, for one). Don't forget that using ear buds in both ears while driving is illegal in many states.

My solution? I use a Shuberth helmet with integrated bluetooth receiver and speakers + a set of "Earpeace" ear plugs. The ear plugs remove all the extra 'noise', allowing the music to come through (from my Garmin, I hate phones). My helmet has a removable battery (about the size of a small box of matches) that gets 9-10 hours of play/charge. I've got a spare and I just swap them out if needs be (takes 15 seconds). This past year I did the American Legion National Legacy Ride over the course of 5 days, averaging 6-8 hours saddle time each day. Never did I run out of battery. If I ever had the time/inclination to run Iron-Butt, I'd throw the charger in my cubby and charge the spare while riding.