First of all: I am a complete beginner. Before using Soundjack (FMB ordered) to play together with others, I would like to stream our house music over the Internet, if possible without the other side having to (initially) install software. Am I completely on the wrong track? What would be a smart solution?

Yes, a Soundjack instance always requires another Soundjack instance to receive a stream. It is (yet) not a broadcast service as known from public TV or radio senders.

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