LP sound buzz when plugged and presets goes to 12'

The Moog Forum Little Phatty & Slim Phatty Forum
1

I find strange thing:
When LP plugged to amp(no else in Main Out or Phones) it makes buzz sound on each preset.
In the moment it plugged all four lights run to 12’(on all presets run to 12’)
Why it may by?
All my familiar engineers only show ??? in his eyes…

2

Check to make sure the outlet that is being used is properly grounded. Also, try plugging both the LP and the amp into the same outlet to avoid a ground loop.