I have never used nor seen an optical audio connection before, so please bear with me. Laugh if you must. I have a Panasonic DVD-CP72 and I'm trying to connect it to my brand new Harman Kardon AVR125 using a Toslink-to-Toslink optical cable. Connecting to the DVD-CP72 optical jack is no problem. The "male" Toslink inserts easily into the "female" jack on the back of the DVD-CP72 player. On the other hand, the AVR125 receiver's optical jacks have me totally confused. The optical jacks on the back look nothing like the jack on the DVD player, and for the life of me I can't figure out how to connect the "male" Toslink on the other end of the cable to the "mushroom-like protrusion thingy" on the back of the receiver. I've tried inserting the small cylindrical protrusion thing on the end of the Toslink into the hole in the top of the receiver optical jack, but it won't insert easily, and it just doesn't seem right. Should I force it in? I have got to be totally missing something here. Can anyone please help me out?