Hi,
I have installed the DAC+ DSP hat on my RPi 4 and followed the instructions on https://www.hifiberry.com/build/documentation/configuring-linux-3-18-x/ to install the driver (#dtparam=audio=on, dtoverlay=hifiberry-dac, dtparam=i2s=on in config.txt and pcm.!default {type hw card 0}, ctl.!default {type hw card 0} in asound.conf).
Unfortunately, the DAC does not work. Although aplay -l shows only the hifiberry, mplayer does not play any sound for flac and mp3. Also playing wav files leads to a periodic popping sound. Finally alsamixer says "This sound device does not have any controls." How can I address this problem?
Thanks,
Mohammad