tried to connect the pc to the stereo ages ago via a cat 5 ethernet (lan) cable, and thought it worked a treat. I was being lazy and decided i didn't want to run another cable under the house, and why not use the cat5 that was already under there?

so i used 1 twisted pair for the earth, another for left and one more for right. The fun bit came wiring a 3.5mm "headphone" plug to rj45 (the ethernet plug), and then a rj45 to rca (the standard stereo plug). I thought all was good until there seemed a lot of 50Hz interference on the music. so i shortened the cat 5 cable, useing a new crimping tool - went ok. Then i noticed only 1 speaker is working. So i ran a second cable up the stairs to check the new plug - all seems ok. so then i used a rj45 joiner and the test cable to make a loop, and then checked each of the 8 wires with the multimeter - all good. so then i looked at the sun cat5 cable i used to patch into the rca lead, and it is wired DIFFERENTLY to the cable i used. So i grabbed another i made and now all is happy!! And the sound is SOOOOO much better.
why is there a difference? The sun cable is not a cross over (i don't think so anyway)
. dunc