Pioneer MVH-S21BT Digital Media Receiver features built-in Bluetooth, enabling both hands-free calling and audio streaming. You can listen to music from your Android device or USB flash drive via the front USB port. Built-in MOSFET amplifier delivers up to 50 watts to each speaker (up to 4 speakers). For even more power, you can use the 1 x RCA pre-out to hook up another stereo component, like a subwoofer or an extra amplifier for the rear speakers.