Should have known better when I returned one of my pedals for the third time because of the very annoying high-pitched idle sound caused by a generic PS and poor pedal's wiring. Then I tried battery charged multi-power supply, which did help lower the pitch but not eliminate it. Of course, the only solution left to keep otherwise good-sounding pedal was to choose a proper isolated PS. And Rockboard ISO was a perfect choice. Eliminated the high-pitched noise completely! With versatile power settings and an additional usb port is a must have for any kind of pedal setups.