Loud Electrical Hum from Sub Preout when units are in Standby!

[Pleyel]

Hi Folks

I’m getting loud electrical hum from the sub pre out while the unit’s are in standby mode, loud enough to trigger the sub to turn on, and stay on. When you turn the units on, the hum goes away. It’s the same for the master and the slave outputs. Anyone got any thoughts?

440 Pro Core Infinity
2.1.0 + 12.1.2
PowerSoundAudio S3000i Sub

Thanks in advance

Did you try making sure both the amp feeding the sub and the sub are powered from the same (earthed) power strip?