I just got a used power station very very good condition even still had box and stickers from a trusted seller, I don’t know if this is common but when I put it in operate mode my volume is lowest at 12oclock, when I turn it far left and far right it’s loud, also tapping the “amp in” seems to make the volume go quiet and loud, the cables are all brand new.
No, that’s not common.
What all do you have connected in the way of external gear. I usually perfer to weed out any external connections and possible ground loops before looking for an internal symptom.
Dave
I run an Axe fx 3 in the effects loop of my mess boogie Mark IV and a 4x12 marshall cab and the axe fx works great in the loop I’ve done it for some time now it was only when I tried using the power station this happened 
, it’s like sometime it attenuates and I tap the amp in and get way loud again, my biggest mystery is how come the volume knob is quietest at 12oclock. I took it to a well regarded local electrician who has worked on many of my tube amps for years, I know that breaks my warranty but I still love to give you any information he finds or doesn’t find and I’d still like to troubleshoot with you.