ALLO product & RPi4

[allo.com]

USB can be used to play both FLAC and DSD

[allo.com]

You want to play in the same time FLAC and DSD ?

 

   Thats not possible .

[allo.com]

Ok USB can output both flac and DSD and coaxial as well(but at lower sample rate)

 

  Like DuckToller says , USbridge Sig + Digione Sig will allow you to use both coaxial and USB (one at the time , USB output or coaxial has to be chosen in the software)

 

 USBridge sig was designed not to have noise on USB and Digione Sig was designed not to have jitter (since on coaxial clock is sent to DAC from the spdif stream)

 

 

[allo.com]

Yes USbridge will output (USB) to your DAC up to PCM 32/384/DSD 512.

 

  Regarding NSA etc...this is done in software. Please check Moode , Volumio . PcP and many other OS on how to do that.