This amplifier uses 6J5 electronic lamp and high quality NE5532, and BT4.2 version does not support APTX function. The main filter capacitor adopts 470 UF/25V, and the coupling capacitor adopts 1 UF capacitor. PCB adopts 1,6mm thick double-sided sheet, 2,0oz copper thickness, and the whole tin spraying process provides excellent current flow efficiency. Characteristics: Using 6J5 electronic lamp and high quality version of NE5532 and BT4.2 does not support APTX function. The main filter capacitor adopts 470 UF/25V, and the coupling capacitor adopts 1 UF capacitor. The resistor uses a high-precision chip resistor and the highest quality circuit board. The circuit board adopts 1,6mm double-sided sheet, 2,0oz copper thickness, and the whole tin spraying process provides excellent current flow efficiency. The layout of the board is reasonable, beautiful and has little current. The input and output interface is made of gold-plated RCA lotus plinth, which is durable and beautiful. The three knob design improves all the details, clarity, directness, richness, tone associated with your music, you can easily get both powerful and sweet sound. Technical data: Name: Preamplifier Material: printed circuit board Colour black Power Supply: DC12V Product Size: 137 * 104 * 41 mm / 5,39 * 4,09 * 1,61 inch Package Weight: 500g/1.10lb List of things to pack: 1 * preamplifier