You don't pair an Express to anything. It's a very simple device, and doesn't pair to anything.
If you have a Streambar, that is a Roku device. The Express is superfluous in that setup. You could do what you want without the Express.
However, if the projector outputs audio, it will work with the Streambar as it would any sound bar, and you could use the Express to play.
But I'd take the Express out of the mix and just use the Streambar with the projector.
Roku Community Streaming Expert
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