a wall wart is a digital switching power supply,
They're used to power laptops and tablets, also small components like some DACs and streamers. Their design produces dirty power to the audio device and allows noise to flow back down the AC line and contaminate other components.
To eliminate this noise, a linear power supply (which contains no switching circuitry) should be used.
Many of the audio manufacturers offer an LPS for their devices, plus there are many very affordable aftermarket units on Ebay.