Tangent Ampster BT II (Integrated Stereo Amp)This is the most popular model—an all-in-one integrated stereo amplifier designed to power traditional passive bookshelf speakers directly from your phone, TV, or computer.
Power Output: 2 x 50 Watts @ 4 Ohms (2 x 25 Watts @ 8 Ohms).Connectivity: Bluetooth 4.0 (aptX), Optical Digital, RCA Line-In, and 3.5mm AUX.
Key Features: Dedicated subwoofer output, USB charging port, and an automated "Wake-on-Bluetooth/AUX" system that powers the unit up when you press play on your device.