2001 Audi A6 2.7 t Quattro

Just what the title says I'm trying to plug my adapter into my cd changer port once I do I turn the volume up as loud as I can and can barley hear it, this also happens when I just plug in my cd changer and try to play CDs turn it up as loud as it goes and can barley hear it.. Idk why this is happening!! Help please