I've used a Rockbox Boiling Point, Mojo Hand Rook, Wren and Cuff Caprid and Wampler Pinnacle and they all sound good running into the Ace Thirty. The Ace Thirty retains the tone of the pedals but gives it that tone if you were actually playing through an AC30. It also LOVES my Suhr Koko Boost on the mids side to push it even further into drive territory. I'm very happy with it
I've been using my Maxon OD9 with good results. Great tones for Jesus Culture and a lot of P&W stuff. I have also used the boost side of the pedal with the 30 setting as well but find it too loud for rhythm.