There is only one think is important that is a pure noiseless power supply thats it
Though I have very limited experience with RPi, I can absolutely vouch for the above statement. The Teradak linear power supply raised the sound of the RPi + Hifiberry + Moode combo to a much higher level compared to powering it from a battery bank or a wall wart. I think a good linear power supply should be mandatory part of the "Bill of Materials" if investing in RPi setup.
The Teradak also significantly improved the sound of a Peachtree DAC ITx compared to the supplied wall wart adapter.