Here's Genz Benz' description DESCRIPTION The STM-600 is our 600 watt version of the Streamliner™ design. The 300 volt All Tube Class A preamp design is driven by three 12AX7 preamp tubes utilizing six gain stages. The preamp design features an intuitive and highly effective tone network which is a unique blend of a modified passive Baxandall network for the bass and treble along with an active tube driven mid filter, with selectable mid frequencies. This versatile all tube preamp exudes a fat and rich tone that remains articulate. It can be used to simply add warmth to your natural tone or it can be dialed in to provide a wide range of natural tube overdrive. Along with our preamp design that rivals that of many classic tube amplifiers, the STREAMLINER™ 600 also features our proprietary 3 Dimensional Power Management analog technology. Our 3DPM™ adds heft and girth to each individual note, while enhancing the amplifiers responsiveness and headroom. It provides the dynamic and 3 dimensional tone and feel of an all tube power amp design. With its solid extruded aluminum panels, CNC machined solid billet aluminum faceplate and smooth-radius edges the STREAMLINER™ 600 chassis emanates the ruggedness and strength of a world-class touring machine. This brushed aluminum chassis is finished in an anodized Gun Metal Blue color. Simply put, this new design offers a more streamlined approach to finding your voice, yet it still carries forth the GENZ BENZ reputation for performance, reliability and innovation. I'd just say this is a potent little monster of an amp head that can go from clean to creamy or gritty distortion with nice natural compression. I'm really only looking for an Empress Effect multi drive or smaller PA set up in trades. PRICE DROP! Now $450!