Cat 5 cable varied a great deal when it first came out when there was no uniform standards and universal tolerances put in place by the Alphabet standards committees. The powers that be came up with universal standards for North America, and CAT 5E was born. So if your cable is CAT 5 and not CAT 5E there could be a big difference in the cable as far as data transmission. As far as audio is concern, the cable insulation is a bigger factor ( plenum or non plenum). A plenum CAT 5 or CAT 5E cable will most likly sound better than a non plenum CAT 6 cable. Now I have made speaker cables out of plenum CAT 5, CAT 5e, and CAT 6 wire. I like plenum CAT 6 better. First of all it is a thicker gauge wire (in most cases) 23 awg as to 24 awg for CAT 5 and CAT 5E. In my opinion the bass is better (tighter,fuller), mid range is fuller, there seems to be better pace with music. Now this could be all to the even higher tolerances for CAT 6 cable, which is design to do 1 gigabytes 350 MHz. I won't even get into CAT 6E or Augmented CAT 6, or CAT 7 for that matter. OH, and one last thing. To the original poster, I will also let go the same 25'( MAKE THAT 30') of Plenum CAT 6 for FREE. With FREE SHIPPING to lower 48 states only. Just email me. I think there is a time and place for everything. The key is knowing the appropriate time and place.