Sabaj Small Desktop Stereo Audio Digital Amplifier AMP with Bluetooth USB Optical Input Black Silver With optical bluetooth analog Input, Class D digital amplifier with remote control and antenna TPA3116 amplifiaer chip,WM8524 DAC chip and LC89091 digital optical recieving chip.sampling rate is up to 44.1KHZ-192KHZ Body all made of aluminum scrub,effective screen disadvantages battery interference, so that sound more pure. Well selected nichicon capacitor.custom-built air core inductance.Golden RCA and pure copper speaker terminal. Visualized LED digital screen.Simple design but high-quality workmanship What's Covered: mechanical and electrical failures during normal use, 100% parts and labor Get fast repairs or replacements from SquareTrade, an Allstate company 24/7 customer support, free shipping for all repairs, no deductibles or hidden fees Cancel anytime, full refund in first 30 days, fully transferable with gifts SquareTrade Protection Plans are only valid for new or Amazon certified refurbished products purchased at Amazon in the last 30 days. By purchasing this Protection Plan you agree to the Protection Plan Terms & Conditions (http://www.squaretrade.com/terms-standard). Your Protection Plan Terms & Conditions will be delivered via email within 24 hours of purchase A2 class-D digital amplifier Supports optical and analog andBluetooth inputs which can be controlledby remote.It added one more BT4.O and optical input jack than A1.Sampling rate is 44.1KHZ-192KHZ,RMS watts 55W*2. Using WM8524 as DAC which is 24 bit/192khz stereo DAC.That chips features with SNR-106DB,THD-93DB and mute attenuation. Built-in 4.O version Bluetooth module.External antenna best support signal range up to 10meters around.Ultra-low consumption design and fast power on From raw material collection,A2 uses nichicon FW series capacitor and ordered own inductors. CSR8645Bluetooth chip,TPA3116 amplifier chip,WM8524 DAC chip and LC89091 digital optical recieving chip. A2 build EQ inside,EO is EQ off.El is for loudness adjustment.It can increase MID-HIGH frequency when at low volume to keep the sound output balance. Long-press knob is power on/off.Short-press knob is input source switch(in1 optical,IN2 3.5MM analog input,IN3Bluetooth input.)In addtion,we packed with one remote for convenient usage,it Get 10meter range.EQ function also can be on/off by remote. A : DCIN B : Right channel output+ C : Left channel output+ D : IN1optical input E : 3.5mm analog input F : IN3 Bluetooth input G : Right channel output- H : Left channel output- I  : Input and volume display J : Multi-functionknob 1,NICHICON FW Series capacitor 2,Volume controled by electron.That design keeps two channel volume synchronization and be balance.Traditional potentiometer is not able to achieve. 3,Well selected nichicon capacitor.custom-built air core inductance. Golden RCA and pure copper speaker terminal. 4,Visualized LED digital screen.Simple design but high-quality workmanship. 5,Flexible memory function for volume,it will keep last usage volume when you restart the unit if your volume is between 12 and 40 in last usage;if your volume is up 40 in last usage,to keep your hearing.Volume will be as low as 40 when you restart it. 6,Using LC89091 as optical receiving chip,sampling rate is up to 44.1KHZ-192KHZ 7,CSR8645 stereo audio transmissionBluetooth module.Stable output and low consumption. Output power(4ohm):55W+55W/(8ohm):40W+40W THD+N:&lt;0.03% Power consumption:40W Power supply voltage:24V/4.5A Standby power:1W Input jack:3.5mmandOpticalandBT4.0 Output jack:banana plug. Input level:2Vrms        SNR:100dB Chips:TPA3116 LC89091 WM8524 CSR8645 Optical sampling rate:44.1khz-192khz