Built-in audio system with Bluetooth and MP3 player (USB and SD card) for 4 speakers. In-wall system with integrated stereo amplifier for 2 speakers. 4x 20W Class-D digital amplifiers, frequency response: 20 Hz - 20,000 Hz. Bluetooth streaming, MP3 player (USB port and microSD card slot), FM radio, line AUX. Stylish touch control panel. Line output, screw terminals on the back. Includes back box and remote control. The Powerline series features flush-mounted music systems with a built-in amplifier and music player. The sleek, elegant surface with a touch-sensitive control panel provides a minimalist look, allowing your sound to be heard and not seen. All cables and connections are safely hidden in the walls without tripping hazards. Enjoy your favorite music from various sources, such as BT streaming, USB, microSD card, FM radio, and line-level AUX. With the BT streaming function, you can establish a direct connection to your smartphone, tablet, laptop, etc. The touchscreen allows you to control all aspects of the system - just touch and go.