I replaced a 75' run of cheap Monoprice Cat6 that goes from my office router, down into the basement, and up into the living room stereo system with a 50' run of Blue Jeans 6a for the purpose of getting the most out of my TIDAL subscription.
The difference was very easy to detect. I'd describe the sound as cleaner, purer, and better-defined.
01-14-15: Cymbop
I believe you when you say you could hear the difference between the two cables. Blue Jeans' uses Belden cable a highly respected data cable manufacture, Monoprice doesn't say whose cable they use. They just say it is pure stranded copper. The construction of the raw cable can make a difference how the cable will perform.
I would discount the differences in length of the two had anything to do with the reason why you heard a difference, but I would like to know what you did with the additional 25' of the 75' Monoprice cable. Just guessing you coiled up the excess 25' of cable at the switch end. If that is the case, the next question would be how tight, rough physical diameter of the coil of the wire? I have found, and don't know why, that can cause errors on a PC connected to a network in the case of horizontal installed LAN cable. Testing the cable that has the excess cable coiled up in a small diameter coil with a scanner might only pass marginally. Increasing the diameter of the coil would increase the test results of the cable.
Best practices say two data cables should be installed at every work station. If you were to compare the certification test reports of a work stations two data cables that were installed at the same time, same cable manufacture, terminated on the jacks on both ends by the same person, the cables will not test out the same. One will test better than the other. And sometimes the differences can be quite a lot with both cables still passing the scanner test.
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