Walrus Audio Iron Horse Distortion The Iron Horse is a return to the classic distortion: thick, punchy, riffy and rowdy. It is full of high gain and perfectly made for the rock guitarist in need of thick rhythm or cutting solos. Dial back the gain and it can be used as a thick, warm overdrive. The Iron Horse has three distortion modes operated by a toggle switch that changes between different clipping diodes providing more versatility in shaping the tone of the distortion. It has three control knobs: Level, Tone and Distortion and True Bypass switching.