If it's quiet with a battery and squeals with a wall wart, then it's not the pedal that's the problem, it's the wart. A lot of cheaper P/S's have problems like this, particularly with "gain" pedals, which will naturally amplify any noise that's present. We see this quite often here. Suggest that you either run it with a battery or invest in a higher quality power source. The Visual Sound 1-Spot
is a popular choice.
Well thanks, thats good news i guess but its funny you mentioned the 1 SPOT because thats what i was using. I live in an old house though with terrible grounding issues and i'll see how it responds to other outlets in the house.