Very sophisticated, all analog circuit. Quiet EQ and gain, even quieter preamp. Has a thicker, warmer tone quality even in overdrive, but we have modified it to allow more edge and clarity of extreme highs to pass through slightly "silvery" sounding. Tone control of highs will be more effective to darken or brighten guitar. Unit has effect send, XLR out, headphone out, and input for optional channel switching pedal. Like new condition, all cleaned, calibrated, and serviced.