@mikhailark On your point about local file playback, Roy Gregory was surprised to find a similar improvement with his Wadax server/streamer (see page 5 herehttps://gy8.eu/review/magnificently-minimalist/5/. I agree with his hypothesis that if there is less RFI going into a server/streamer via the ethernet connection then that will logically affect even local file playback.
Re RFI, I mean both. Yes a switch generates its own RFI but steps can be taken to minimise that generation and the massive reduction a good switch makes to reducing incoming and therefore "net" RFI is clearly audible.
Disclosure: as per my profile, I design and build switches for audio purposes so I have spent loads of time working out what can/does and can’t/doesn’t make a difference to sound quality.
My key point in contributing to this thread is not to argue the merits of various RFI-mitigating approaches (that has been and can be discussed elsewhere). Here I simply wanted to point out the clear difference between clocking in the asynchronous ethernet domain and clocking in the synchronous bitstream domain.