It has a Microphone input too. Not sure how well that will work for a line in, but I guess we'll find out.

EDIT: Apparently, the current firmware for this module doesn't work in "Master" mode to send audio to another device. It only works in slave mode to receive audio. Perhaps this is a "no go."

EDIT2: It appears that there's a different firmware RN52SRC that is designed for this, so perhaps this is, in fact, a "go". demo.