I have seen some serious PA speakers on big LiOn batteries (10″ or bigger, don’t recall exactly) that packed quite a punch. Some brands I know here in europe are Fohhn (absolute top quality but matching prices) and Proel (Italian brand, better priced).
With weddings it’s more about the audibility of speech than it is about gut-wrenching pounding bass. So setting up 4 or more smaller speakers (I would audiocable them from the source btw) to cover a bigger area with a more even sound level. And then you don’t need really big speakers.
Again, if you are in Europe, try to rent some Fohhn gear. I can promise you will have great outdoor sound (have done some outdoor gigs with them, including a funeral) and everyone will be able to clearly hear each word spoken and music played.
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