i use a Thundertomate Hilborne Booster, same as Gwem's. fabulous little pedal, really brings the right amp to life. i've mostly used it with my Matamp AB15, and it's just a glorious sound. i tried it with the Genz Benz El Diablo and it just really added noise, but then, that amp doesn't really need a boost! :)
i, too, am intrigued by the hawk booster