Hi guys! Hope y'all are healthy... Bass on! I have this configuration: Ampeg SVPCL Pre + SVT-450 Amp + SVT-610HLF! Not a daily user, till nowadays, with this disease, get time off to pratice. i have used WD 40 oil to clean preamp knobs which as due to humidity are crackling. i thought that was nearly solved... but i have a mindless noise delivered by 610HLF even without nothing connected! What could it be? Hope some "expert" give me hints! Thanks for it.