Audible illusions L3A Tube PreamplifierNEW L3A TECHNICAL FEATURES Circuit Design is Pure Class A, Single Ended Triode, Zero Feedback, Dual Mono. Audio Circuit has no Cathode Followers or Buffers. To prevent unwanted AC induced distortions, the L3 features an External Power Supply housing three separate supplies and a large shielded, custom wound transformer. In the main chassis, four separate, fully regulated FET power supplies drive the audio circuitry in addition to separate filament