Connect "XinYi". 2.APP Download ： Mobile App market or App store， Search："Sinilink" . 3.APP Usage: 1. Turn on the Bluetooth of the mobile phone and turn on the location positioning; 2. Enter the APP operation interface --> Click the yellow dot --> Click Bluetooth device --> Search Bluetooth --> Connect "Sinilink-APP"【TPA3255 HIFI CHIP】The XY-S350H power amplifier board uses two TPA3255 power amplifier chips.Support wide voltage input:18-36V, power up to 220W*2+350W (PMPO).【TREBLE & BASS CONTROL】If you are tired of an amplifier with only one volume knob, then you feel right, because you have further requirements for audio. By adjusting the high and low frequency knobs of the XY-S350H power amplifier board, you can make the sound more layered and make the bass more shocking.【HIGH COMPATIBILITY】The DC adapters on the market (plug size 5.5mm*2.1mm) can basically meet the needs of the XY-S350H Bluetooth power amplifier board. If you dont have a DC plug, please dont worry, you can also directly connect the positive and negative poles of the wire to the power socket of the amplifier board." />