I'm looking for sources for the ideas that either a singer, composer or style of music can infuse a spiritual influence in a song, which would then influence the listener.
The only sources that I am currently familiar with are Rabbi Nachman in Likutei Maran, and the Gemarah crediting the fact that Achar would constantly sing Greek songs as a reason for him becoming a heretic.
I personally don't see any proof from the Gemarah as Greek songs were likely actually infused with Greek philosophy in their lyrics and that could be what the Gemarah meant.
Does anyone have any other sources?