We have the power supply for the electric piano used in our church. The electric piano is decoupled via a DI box connected to an audio system. Nevertheless, our bass box hummed once we connected the power supply to the electric piano. We have tried everything possible to rid the hum (DI box with / without ground lift, filter the output for bass box, different power outlets, ...). Only after replacement of the power supply, the hum was gone: We now use again the old original power supply of electric pianos (with now repaired cable outlet). The problem is apparently the technique: The PA-130A is a switching power supply, the old original power supply has a transformer in it. Apart from the power supply is working properly so, for stand-alone use perfectly fine.
