BTL, Alto - M-20 Audio amplifier

Audio amplifier plus 4 professional speakers.
Compact stereo audio amplifier (model AK-699D).
Its main function is to receive an audio signal from various sources, amplify it, and send it to loudspeakers (passive speakers) to play music at a higher volume.
What it’s for and how to use it
Amplify the sound: Connect passive speakers to listen to music at home, in the garage, in a camper, or in a car.
Play music from USB and SD/TF card: You can insert a USB flash drive or a MicroSD card containing MP3 tracks to play them directly.
FM Radio: Thanks to the built-in telescopic antenna, it also works as an FM radio receiver.
Audio controls: It has front knobs to adjust Volume, Bass, Treble, and Channel Balance (Balance).
Versatile power: It runs on 12V DC power, making it ideal for both home use (with a 12V wall adapter) and use in vehicles (cars, boats, campers).