One thing to know about the 3-Pros also is to ignore the red input light. A lot of folks set the input gain so that it doesn't light up red, and then they wonder why the amp isn't as loud as they would like. Be sure to use your ears, not your eyes to set that input. Also - play around with the Tube Gain (Plate Voltage) knob. All the way to the left will give you a softer tubey sound, all the way to the right will give you a slight boost in volume and will sound a bit more defined.