When you test an Ethernet channel like an Industrial 2PR CAT5 with massive noise and EM all about that are far, far worse than the FCC limits for home use limits, we test ZERO BER! So yes, we test Ethernet every permanent link installed in real world apps and zero BER is the requirement to pass and this based on an internal cable measures like you get from Blue Jeans Cable with your assemblies.
If we want to play with the “sound” it isn’t the BER doing it. The Ethernet NIC cards ASIC isn’t remotely aware of what the cable is at all, it just chugs along as long as the signal is above the noise limits. And, those signal limits are -3dB and more BELOW the actual noise level! Ya, it works when the noise is LARGER than the signal. YIKES.
We aren’t even close to that Shannon’s law signal bandwidth with home networks.
BER isn’t the problem in audio but poorly designed DA and AD blocks that are non linear with noise. Each Ethernet cable, due to the internal lay design, can have varying spectral noise floors, but they ALL pass the 100 meter noise floor limits if they are legally tested Ethernet products (those pesky tests Blue Jeans supplies). The proper balanced circuits at the end of the chain are your problem if there is one. That ground FLOATS between the two wires, so RF is stripped off (it is common mode) and how Ethernet works to remove noise. It uncouples the GROUND so it can eliminate noise and that includes RF. -2V from +2V is 4 Volts. -1V from +5V is still +4 Volts. The added 1 volt of noise made no “difference” to the output of 4 Volts as an example.
Are both side of a balanced circuit “perfect”?. No, we have a CUB, Capacitance Unbalanced to Ground requirement needed for zero BER, so that’s all in the math too. And, CUB is length multiplied and we are so short that CUB isn’t even, or could be, a problem yet.
We can’t hear “bits”, but we can hear ANALOG time based EM wave changes, THAT is what our signal is after all. No change to the EM wave somehow and we don’t have a change. It is that simple to say. Now we need to find the CHANGE from set-up A to set-up B.
I use a PS6+ Ethernet with my PS Audio DS DAC to my UPnP/DLNA , and a 2 meter USB cable from the PC from my SD3100HV DAC. Neither has issues with noise or “black” backgrounds. The filters (firmware) do sound different on both DAC’s but that’s the DA conversion algorithm not the Ethernet or USB cable. The bit perfect data hasn’t changed.
I do use a P20 so my grounds are re-referenced to one point, with a stable 120V putput. Heavy BAV power cords to preserve the ground values near the same. My system is very “quiet” on one leg of the box and with grounds re-referenced through the P20.
I don’t suggest one thing to you and do another. I make changes ONLY where the data supports the effort and cost. I’m all for eliminating calculated or measured differences within a budget. The others? Not so much.
Best,
Galen