I purchased this unused outlet item and only tested it at home to confirm the sound. It has been stored at home since then. Although the warranty is not included, it is almost new. When something is combined, is something lost? When something is lost, does the whole increase? And did you get "gain"? The ～900 is a powerful fuzz pedal that combines two JFET gain stages. It is a descendant of the Four Eyes, which was once produced by Fairfield Circuitry, and adds a wide gain range and high-quality harmonics. The ～900 has four interactive control knobs: INPUT: Input gain FUZZ: Second stage gain BIAS: Second stage bias gain VOLUME: Volume By combining and operating these, you can freely control "gain" and tone. Any fuzz is a friend of the ～900. The ～900 is powered by a standard center-negative DC9V adapter. Batteries cannot be used. *Turning the BIAS knob will produce a crackling sound, but this is a circuit specification.