I found a solution.
It's a hack but it works.


// play_mp3_control_example.c ...

ESP_LOGI(TAG, "[ 5.1 ] Start audio_pipeline");
set_next_file_marker();
audio_pipeline_run(pipeline);

/* START SOLUTION */
gpio_set_level(21, 1);
gpio_set_level(22, 0);
gpio_set_level(21, 0);
gpio_set ...

I found strange behaviour. If you run the example mp3 player and then disconnect and reconnect one connector between boards A and B, then the sound volume will be high. After pressing the reset button, the sound will become quiet again.
https://ibb.co/0DDnBHT

Hi!
I have the same problem.
My device consists of two boards. https://espressif-docs.readthedocs-hosted.com/projects/esp-adf/en/latest/_images/esp32-lyratd-msc-v2.2-side.png
I ran the mp3 playback example and then removed and put back the top board. After that, the sound is heard loudly. After ...