How do I prevent an Android from rerouting audio to external device?

I have a pico projector to which I hook up via wifi (and at other times via hdmi)
Naturally, audio also gets rerouted to HORRIBLE speakers on the mini projector.

My phone speakers, on the other hand, are actually pretty decent and around 500% louder than the miniscule mono speakers on the projector.

So the question is, how can I prevent my phone from rerouting the audio signal.
Or, is it possible to split the audio, so that it plays both on the phone and the projector.

I am using android 4.4 rooted.

Thank you very much.

Your help in this matter is very much appreciated.

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