I am machmir on only listening to music that was performed by a Jew, but i don't really understand it. Does anyone know what is the source for this? Does Matisyahu perform with only Jews?
See Igros Moshe YD 2:111 where he raises issue of church influence which relate to the players' intentions, the words, and the instruments. Jews presumably would not have suspicious (regarding idol worship) intentions.
Here's a summary of Igrot Moshe Yoreh Deah 2:56, which says that the bottom line is that "it is forbidden to listen to non-Jewish religious music ... However, if the song is written and/or song by a non-Jew but has no religious purpose, then there is technically no prohibition."
I heard a prominent Rabbi say that it was mutar as long as the lyrics and clean and the beat will not make one do inappropriate things. (See Rambam's comment on Avots 1:16)
In a Q&A session by R' Hershel Schachter I recently heard, he explains (I forget based on who) that artists put some of their essence into the art they make, so when you consume art, you internalize a little bit of the artist's soul. So, he advocates against listening to music composed by non-Jews.