If you have any questions, please contact customer service first, do not open disputes easily, thank you! Mini size and unique design: built-in tube makes you have a tube amplifier which can be held by one hand, convenient to carry and can enjoy HiFi music everywhere. With built-in battery protection circuit: battery lets your listening feast without time limitation. It can't be turned on during charging and will power off automatically after fully charged, and charger LED will turn to green.
Full, delicate and soft sound: warmer than transistors, independent op amp and power supply inhance the SNR and degree of separation, less interplay and higher sound quality. High-end making material and craft: using gold-plated socket, original nichicon electrolytic capacitor, original DALE resistors and precision ring resistance. The difference between B4 and B4-X: 1. B4-X is a dual-mono balanced version. Its left and right channel are amplified by independent components, and power supply, tubes, and op amp are all independent and symmetric.So the degree of sound separation is higher than B4. B4-X adopts 2 groups of independent power supply (+12V and -12V) for 2 op amps, less mutual effects and can drive 300O headphones. The circuit adopts dual op amp parallel output, with higher output power. B4-X has 3.5mm and 2.5mm, 2 kinds of output interface, suitable for most of balanced and standard headphones.
Tube: USA RAYTHEON JAN5899 ×2 Op amp: NE55322 (can be upgraded) Lithium Battery: 12V, 1000mA Charging time: 2-2.5 hours Working time: 4-4.5 hours Output power: 450mW SNR: 105dB Suggest load impedance: 16-300O Output: 2.5 balanced Jack1, 3.5mm Jack 1 Size: about 115 69 23 mm (LWD) (does not include the knob). 1× Headphone amplifier 1× Power supply 1× 3.5mm audio cable 2× Band. Software sales are not refundable. This item is in the category "Consumer Electronics\TV, Video & Home Audio\Home Audio\Receivers & Amplifiers\Amplifiers & Preamps". The seller is "gogogo4251" and is located in this country: CN.This item can be shipped worldwide.