I made it according JCM-800 lead channel schematics. Capacitors are Wima, resistors in the sound path are metalfilm type. I never use any power (9v) external adapters. Real power (120v or 220v at your choice) toroidal transformer is inside so sound dynamics is wide and nice. There is Marshall "4x12" speaker simulator inside. Pure JCM sound! Look at my other preamps.ru