why do you think Jesus went into a desert, fasted, prayed in the garden, etc etc etc. ... perhaps this was the prime example of "how to know"?

Agree - Jesus is in the best position to know what God want (circular logic, huh!)

Is there anything in scripture about him singing the Psalms? Or chanting Jewish liturgical texts? Taking part in regular corporate worship, even?

Keeping silence seems like the best way to follow his example.

Through history, there's quite a major disconnect between official church teaching on music in liturgy, and actual liturgy which the faithful experience. Enough to raise questions about what we really do know, vs believe.