Review on Fosi BT30D-S Bluetooth 5.0 Receiver Amplifier 2.1 Channel Hi-Fi Stereo Audio Class D Integrated Amp - 50W x2+100W, Perfect for Home Outdoor Passive Speakers/Powered Subwoofer by Cassie Zingone

This tiny amp was paired with a pair of vintage Polk Atrium45 speakers and subwoofer output with a 10" Velodyne subwoofer. Bluetooth simply connects to your phone to play some ringtones. With Bass & Treble on medium settings, the sound was crisp, clear in the mids and highs, but with booming, heavy bass. Bass adjustment did little to reduce boominess. I had to adjust the volume on the back of the Velodyne. Bluetooth range was acceptable for most upstairs rooms, but not with the wide range of powered subwoofers available today, a subwoofer output is a great feature. Bravo!