Not only broaden the frequency response but with better bass extension; Woice is mellow and fine; Overall structure adopts two PCBs; Thickness of the main circuit board is 2mm which is mainly on account of avoiding damage when plugging electronic tube; PCB tops is for decorating shileding and anti electric shock etc.; Design is very user-friendly; Feature: 1. Filter adopts Panasonic 105-degree electrolytic capacitor. 2. Filament filter capacitor adopts ruby enthusiast. 3. Resistor adopts 1% metal film fever resistors. 4. Coupled upgrade AUDIOPHILER MKP capacitors. 5. Electron tube adopts ** "J" class tube. 6. Reasonable alignment background noise is almost inaudible Note: The two secondary output lines of transformer should wired correctly or will burn transformers.