My suggestion is to take your favorite album, convert it to WAV format and copy it to /tmp on your Raspberry Pi endpoint. Next, use the SoX “play” command to play the tracks. Finally, completely disconnect the network cable (also make sure Wi-Fi and Bluetooth are disabled)
This is the same or better than what your system would sound like with the best audiophile switch and network cable in the world. No switch or cable can sound better than no switch or cable at all!
You’ll be playing uncompressed files, and /tmp is often mapped to RAM, so there’s little or no I/O to the microSD card, and CPU usage is minimal since the files are already uncompressed.
If the sound from this test does not leave your jaw on the floor, you will be unimpressed with results from an audiophile switch and $1k AudioQuest Diamond Ethernet cable.