In my embedded system I have this configuration file in `/etc/asound.conf`:

```
pcm_slave.sl2 {
        pcm "hw:0,0"
        rate 48000
        channels 2
        format S16_LE
}

pcm.rate_convert {
        type plug
        slave sl2
}

pcm.!default rate_convert

```

I noticed that since this file was placed in the system, `aplay -L` and `arecord -L` cannot list the PCM devices anymore. `aplay -l` and `arecord -l` are instead working as expected.

If this file is not placed in there, the list is correctly returned. What is this doing exactly? Why is this preventing `aplay` and `arecord` from listing PCM devices?