My setup: Ethernit with static ip – disabled wifi – cpu overclocked – mtu = 746.
Music files are saved on a WD live book NAS. No problems here with the setup.
First I connected the raspyfi with my Audioquest Dragonfly usb dac. Crackles where clearly present with small mp3 or big flac files.
Then I connented it with my Musical fidelity M1 dac. 1 crackle every hour of so…. . I thing because of the resampling to 192 within the dac every noise will be killed .
You need a strong power supply. The normal phone supply is not sufficient. You can hear the difference very clear – no bass, thin … .
Imho this little thing is perfect for my usage. But, please get Spotify working !!!!

For Spotify i use musicbox pi.
Usb dac's are not supported – so I use a Ligawo hdmi to optical converter and this is not optimal.

Karsten