Everything Matters With Digital

One’s and zero’s in Ethernet are detected by the voltage transitioning through zero volts in a positive going, or negative going direction. The twisted pairs in an Ethernet cable, (Tx+ and Tx- for example) are balanced and the voltage swings from +2.5V to -2.5V, not 0V or 5V as in other digital circuits. The timing of the pulses is critical and anything that interferes with the timing will introduce jitter in the receiving device, and smear the resultant sound. RFI is a culprit here. Filtering out RFI in Ethernet cables adds so much to improving sound quality. It’s a similar Sonic result to filtering out RFI on your mains input to your system. Network Acoustics ENO does just that. So called ‘Network Isolators’ are a waste of time.

I like learning the engineering level, but logic alone will lead you to conclude that digital will always introduce loss, unless and until science is able to measure, deconstruct and reconstruct EVERY characteristic that causes us to experience (not just hear) music. There's clearly more to the analog content than the waveform, let alone the density of its deconstruction and the precision of its reconstruction. If this weren't true then the makers of the better audio equipment wouldn't all use listening tests as a primary driver in design choices.

Of course everything matters.  If it were just 0s and 1s all digital would sound exactly the same and be a perfect reproduction of the original performance.
This is very far from the truth.
There are far more variables and unknowables in digital than in analogue and issues that will never be resolved.

The main things that matter in digital are the source files the ADC that converts and  the DAC that converts. If your DAC isn't up to modern specs in regard to isolation, filtering and reconstruction then these other superfluous items can make a difference  but if everything between works to spec it's not that important. Consider how much time and money you have invested in your internet modem the device that reconstructs the analog to digital signal. So yes everything matters some more so than others. 

djones51

... Consider how much time and money you have invested in your internet modem the device that reconstructs the analog to digital signal ...

Huh? What kind of ISP are you using? My modem doesn't "reconstruct" analog to digital. It's digital in and digital out.