ALSA recognizes external sound card but still cannot produce sound

Question

I recently purchased a Pi4 and a HiFiberry DAC+ADC as an external sound card. I followed this link HiFiberry Config to set up the hardware. However, even tho aplay -l listed the hardware, the system still cannot produce sound.

In /boot/config.txt, the audio related part is set up as the following:

#dtparam=audio=on
dtoverlay=hifiberry-dacplusadc

I also set up /etc/asound.conf

pcm.!default {
  type hw card 0
}
ctl.!default {
  type hw card 0
}

I obtained the following information for debugging:

$ cat /etc/os-release
Raspbian Linux 10 (buster)

$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: sndrpihifiberry [snd_rpi_hifiberry_dacplusadc], device 0: HiFiBerry DAC+ADC HiFi multicodec-0 [HiFiBerry DAC+ADC HiFi multicodec-0]
  Subdevices: 1/1
  Subdevice #0: subdevice #0

$ aplay -D default test.wav
aplay: main:828: audio open error: No such file or directory

I also installed SoX on the Pi and I was able to use SoX to send out sine waves after I set up the audio environment:

export AUDIODEV=hw:0,0
export AUDIODRIVER=alsa

Thus I am sure that the sound card works fine, and the problem should be ALSA not working quite well with the hardware.

I am not quite familiar with Linux audio so I'd appreciate any hints and pointers. Thank you guys in advance. I'd be happy to provide more information!

Answer 1

I think your asound.conf should be:

pcm.!default {
  type hw 
  card 0
}
ctl.!default {
  type hw 
  card 0
}