[Closed] Music from OnePlus phone through audio 20 system bluetooth?

I'm wondering if it's possible to play downloaded music from my One Plus through Audio 20 (2005 model) through bluetooth. I can set it up to use the phone but I'm not sure how it can be set up to play the music from the phone. Failing that, I'd download a heap of stuff onto my old 3GS if that was bluetooth compatible.

Anyone successfully paired either for music? The MB audio site doesn't seem to work and I'm failing with my searches. I'm not really after a step by step, just a nod to let me know that it can be done and a few pointers to save me from going around in circles if it can be done.

Many thanks I A!