As someone having extensive experience in digital (and analog) design, although not for audio, it is very conceivable to me that a network switch can make a difference sonically. Not because it affects the accuracy with which 1s and 0s are received; not because it affects the timing with which those bits are received; and probably not because of most of the reasons that are likely to be offered in the marketing literature of makers of audiophile-oriented switches.
The likely reason relates to differences in waveform characteristics such as signal risetimes and falltimes (i.e., the amount of time it takes for the signal to transition from its lower voltage state to its higher voltage state and vice versa); differences in noise that may be riding on the signal; and differences in distortion of the waveform that may be present. In other words, things that affect the spectral composition of the waveform.
Those differences in waveform characteristics in turn may, IMO, affect the degree to which some of the RF energy present in the signal may bypass, i.e., may find its way around, the ethernet interface circuitry in the receiving component and affect circuitry that is further downstream. Perhaps affecting timing jitter at the point of D/A conversion, and perhaps affecting analog circuitry further downstream via effects such as intermodulation or AM demodulation.
One thing that became abundantly clear to me in my experience as an electrical engineer is that signals and noise don’t necessarily just affect or entirely follow only their intended pathway. And the waveform and noise characteristics of the signal that enters a circuit can affect the degree to which RF energy present in that signal may find its way via unintended pathways to unintended circuit points "downstream" of the intended circuit. "Unintended pathways" may include things like grounds within the receiving device, parasitic capacitances, power supply circuitry, or even radiation through the air within the component.
For example, in the following thread ...
https://forum.audiogon.com/discussions/bricasti-m1-dac-vs-ps-audio-direct-stream-dac?page=9 ... two members reported that inserting an inexpensive Netgear switch between their router and the ethernet interface in their audio system resulted in significant sonic improvement. One of those members, whose system is of exceptionally high calibre, was extremely skeptical initially, but ended up saying "I can’t believe it."
None of this is to say, though, that a given switch will provide benefits that are consistent from system to system, or that there will necessarily be much if any correlation between the cost of a switch and the benefits it may provide.
Regards,
-- Al
