Features High-end Chip combination: TI's TPA3116D2 amplifier chip as core, whose modulation power can up to 1.2MHz and its distortion below 0.1% even at large power. NE5532 op-amp, whose extension and dynamic, details performance and sound field are very good. CSR64215 Chip supports Bluetooth 4.2 APTX, further transmission distance and more stable signal connection, make it easier to enjoy HiFi wireless music and convenient to switch different music. Using plug-in 6J4 vacuum tube, which has especially good performance in reducing sound distortion, and the sound is soft and thick, sweet and touching, showing ethereal, transparent and fullness feeling. Convenient to replace other tubes you like. Equipped with 24V power supply, max output power up to 50W*2, can easily drive most home speakers. Gold-plated RCA / Banana interface can avoid sparks when power plug in. With overheat, overload, short circuit protection. Delicate, compact and strong appearance design, aluminum alloy shell, gold-plated interface brings you visual and auditory feast. Strong compatibility and control ways: compatible with all speakers on the market, with stereo headphone output, potentiometer knob and tact switch, can avoid shock sound when your toggle switch, no pop noise when Bluetooth connecting. With Bass and Treble Control, can work with MP3, CD, DVD,TV, PC, iPhone, Smart phone,Android phone, iPad, Tablets, Turntable, etc.),It is also suitable for Bookshelf/ Computer/ Desktop/ Theater audio system and so on, different matching brings you hear beautiful music anytime and anywhere. Parameters Power supply range: 12V-24V THD: 0.1% Frequency Range: 20Hz - 20kHz (±3dB) SNR: ≥ 98dB Input sensitivity: ≤ 280mV Load impedance: 4-8 ohms Headphone impedance: 16-64 Ohms(recommend) Max. Output power: 50W*2 4Ω Bass adjustment range: ±6DB Treble adjustment range: ±6DB Input mode: Bluetooth / RCA Output mode: Banana Jacks / Headphone Jack Bluetooth Transmission Distance: about 10m (without interference) Dimensions: (L)129mm*(W)98mm*(H)33mm Net weight: 400g Notice: 1. Working indicator: power on it will be red; choose Bluetooth input mode it will flash red and blue alternately; when connect Bluetooth successfully it will be blue. 2. If there are router near by the Audio amplifier, the Bluetooth transmission distance will be interfered,so please confirm stay away from the router when you use it. 3. Headphone output with priority, when connecting the headphone output, the speaker will automatically disconnect. Operation Steps 1. Make sure the VOL button to the minimum. 2. Connect the left and right speakers according to the interface instruction of the rear surface, and pay attention to distinguish positive and negative. 3. Connect the sound source that needs to be used(Use Bluetooth transmission to refer to the 5th step) 4. Connect to power, press the power switch. 5. Switch to Bluetooth input, the light indicator flickers, and the blue light remains on after the phone is connected successfully. Packing List 1*Amplifier 1*24V/4.5A Power Supply 2*6J4 Tube 1*Bluetooth Antenna