OP, know your audience. This is a long established forum geared toward the Appalachian Trail. Most posters here are older and more conservative/traditional/whatever when it comes to the outdoors. You will likely find zero support or recommendations for this type of request.
You will probably get a decent response if you post on one of the reddit subforums (and you will no doubt catch a lot of **** there too
)
Try r/backpacking, r/campingandhiking, r/campinggear, or r/ultralight if you have thick skin.
I assume you are talking about a speaker to use if your group is hanging out by yourselves on a peak, bald, meadow, lake, river, campsite, etc.
If you plan on using a loud speaker actually on the trial you should beware of grizzlies, mountain lions, rattlers, and ticks. They LOVE loud speakers.