I just can't leave this alone.
In my humble opinion...if I choose to camp so close to you (whoever you are, wherever you are) that you have any chance at all to irritate me at camp...then that is my fault. I chose my location poorly. Bigger lift. Larger tires. More pinstripes. Further away from shore power. That will fix it. Same goes the other way. If you choose to camp within a distance that permits me to irritate you...then you are doing it wrong.
Right?
I don't know about everyone else, but I go camping to get away from other people and social responsibilities. I try to stay as far away from everyone else as I can without actually having to get off my lazy behind and leave the road. If I want to listen to devil music or bluegrass at camp, I do. At any volume I like. So far, nary a deer or woodchuck has said a nasty word about it. Well, not to my face. An elk mouthed off to me on the Interwebs last week. I told him exactly what I thought of him. Online. From the safety of my Grumpy-Couch.
As it happens, I use headphones at camp because they are easy and the volume level is the same no matter where I am around camp. And, they are wireless. Wireless is good.
Trust me, my decision to use headphones has nothing to do with the delicate sensibilities of others.
We go out of town to pretend that we live a different life in an easier time, if only for a day or two, however we see fit, but then some of us choose to hang around campgrounds with two dozen other families only to complain about the nature of people? Methinks these people like to complain due to the position they are putting themselves in. Maybe they yearn to complain about the same crap in a different location?
To the OP, I hope you will listen to any music you like, with any headphones, boom boxes, or speakers that you like, wherever you camp. If anyone complains, just smile, hand them a complimentary Geritol, feed them beer until the Geritol kicks in, and go about your business. You will of course, need to keep a couple of Geritol on-hand. Judging from the aggressive anti-musical posts in this thread...maybe more than a couple of Geritol.
Now, to the OP's question, I've been wondering about the same thing and have been looking at the
Festool Sys-rock (because I have some of their tools and batteries, and often use their
light around camp. They each use the same batteries, and these batteries last forever. Online reviews for sound quality seem to be less-than-stellar though.
To the obvious delight of many grumpy old men here, the Sys-Rock will not be loud.