I have the Metal Muff w/top boost, and a Boss MT-2 Metal Zone. Until I sent the MT-2 to Keeley Electronics, I thought it sounded HORRIBLE. TOO much mids!!! It has soooo much mid tone, it sounds digital and fake. With the Keeley mods on the other hand, sweet tone, and musical sounding. The Ultra mode can blow your speakers if you don't watch how much bass you have eq'ed in. The EH Metal Muff gets my vote, even with the Keeley mods, my Muff still sounds WAY better.