SW1X Audio Design™ PRE I Performance Level 1 Line Pre-Amplifier   The PRE I is a pure class A, Output Transfomerless (OTL) line pre-amplifier with Power Valve Output Stage. Employing El84 power tubes at the output makes the PRE I a smaller brother to the SW1X PRE II Pre-amplifier. It is great enhancement to any … Continue reading SW1X PRE I Line Pre-Amplifier