Summit Audio TD-100 Instrument Preamp and Tube Direct Box 12AX7A/ECC83 tube Transistor output section Tube loading and output gain controls Polarity reverse Ground lift Signal and peak LEDs Works great as a tube headphone amp The Summit Audio TD-100 is an instrument preamp and tube DI that brings true high-end audio quality to home studios An excellent-sounding input stage for digital recording, adding personality and quality to the signal before it hits the converters 12AX7A/ECC83 tube provides milky warmth Transistor output section uses 24V rails to boost the tube sound with no added coloration