The Rolls PB23 is for powering phantom powered microphones with 48VDC. Since the unit uses a 100KHz switching power supply there is no audio noise generated. It has an output pull down resistors so it will work with any mixer.
Rolls PB23 Features
Single-channel switchable 12/48 Volt phantom power supply with all-metal case
Power on LED
Noiseless 100 kHz switching power supply
Output pull down resistors for universal mixer compatibility
Dual 2.5mm DC jacks enable multiple units to operate off of one AC adapter