I would think you can connect the earphone output (mp3) to line-in (receiver). To insure the speakers don't get blown, just be sure to turn down the volume first and increase it gradually.
I have a Sony STR-DE685 receiver. I purchased it about 6 years ago before MP3 players were the newest rage. I was wondering if there is a way to hook up my ZEN V MP3 player to the receiver so I can hear the music from my audio system? I don't want to do anything that would blow the speakers or the system. Thanks.