ETHERNET CABLES

If you are using ethernet to connect to a DAC, I recommend that your communicate with the manufacturer.  For example, DCS recommends an Unshielded CAT 5 cable rather than a potentially more expensive and in particular shielded cable.  In fact, they recommend AGAINST a CAT 6, 7 or 8 shielded cable.  They explained to me that the reason is the design of their circuit-- what they do with the incoming signal (voltage).  

Another + on Blue Jeans Ethernet cable I didn't think ethernet could make a difference at all decided to give BJ a try cause they were cheap $17 for a 1M cable bought two and got a nice increase in clarity from a lower noise floor.

For those who like to delve in some more:

https://www.thewelltemperedcomputer.com/Intro/SoundQuality.htm

I wanted to provide a few more details that may be helpful. What is important to remember is while there is signal degradation that occurs in the channel (cable) the processing inside the network receiver and transmitter (pre-equalization) overcomes the signal degradation. Plus, we are talking about a very short run between audio components. The engineers who designed the Ethernet system know what they are doing.

Ethernet cable consists of 4 twisted pair conductors, so 8 conductors total. Each twisted pair carries a differential signal meaning the voltage on the pair is not referenced to ground, but is the difference between the voltage on the two conductors that form the pair. The audio world understands this as being very similar to a balanced audio cable. Therefore, if noise or interference does couple into one or more of the pairs it does not matter because it will for the most part couple into both conductors, which will not change the value of the voltage difference between the two conductors. This takes care of noise, EMI, RFI that may couple into only conductor, and any small amount that couples into only one conductor is accounted for by the slicer that I described above. This is a good link.

As to shielding/grounding, it usually unnecessary unless there is a specific reason and can actually harm the audio outcome. One reason it is not needed is because the signal is a differential signal as discussed above, and the signals values are not referenced to a ground, but to the other voltage value of the two twisted pair. Second, the shielding with grounded will couple one device chassis ground to another. If/when once devices ground is at a different voltage than the ground value of a second device, then couple these two together with a grounded end to end shielding will couple the bad or non-zero ground into the other device(s). In my opinion, if this finds its way into analog devices such as the DAC, where the analog signal exists, that could spell trouble. One might think ground is the same everywhere, however each device may have leakage, coupling, interference, or a bad ground. We don’t what that device’s poor or different ground to leak into other device chassis.  We don't want that coupled from one device to the next.  Trust the designers of the Ethernet system. Grounded/shielded cables can be needed for industrial applications or where specific issues exist, but not for typical 3 foot runs in an audio system.

This is a good link that explains the issued better than me, with multiple posters each providing the information slightly different with pictures. I find this help me understand.

Finally, as to retiming, the data gets retimed at every network device, such as at the switch or router or streamer. This can be performed by retimers, or other hardware in the network interface This is all taken care of so we don’t need to worry about it. This link is a good screen shot because it shows the eye diagram I reference above, with and without re-timing. Notice the improvement due to the retiming module Keep in mind, the digital signal is completely regenerated within the network interface after retiming anyway.

The Audioquest write-up is from the marketing department.  The first paragraph may have validity for analog signals but neither their long grain copper nor the polyethylene insulation will make an audible difference to a digital signal. The second paragraph basically supports their use of CAT7 cable, and/or any other CAT7 cable.