Advanced 2.1CH Bluetooth 5.0 Receiver Amplifier. You can connect passive speakers/passive subwoofer/powered subwoofer for a nice stereo sound system.

Professional wireless amp with subwoofer frequency, SUB volume, master volume/bass/treble control. No pop sound, no audible noise during the connection. RCA inputs too. Easily pairs with any phone.

$100 when new.