In trying to fault find, I set things up as a DAC+ Pro in Volumio, shut it down, removed the overlay line in config.txt, powered back up and I can now see the card: -
volumio@volumio:~$ aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: ALSA [bcm2835 ALSA], device 0: bcm2835 ALSA [bcm2835 ALSA]
Subdevices: 4/4
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
card 0: ALSA [bcm2835 ALSA], device 1: bcm2835 IEC958/HDMI [bcm2835 IEC958/HDMI]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: ALSA [bcm2835 ALSA], device 2: bcm2835 IEC958/HDMI1 [bcm2835 IEC958/HDMI1]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 1: Headphones [bcm2835 Headphones], device 0: bcm2835 Headphones [bcm2835 Headphones]
Subdevices: 3/3
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
card 2: sndrpihifiberry [snd_rpi_hifiberry_dacplus], device 0: HiFiBerry DAC+ Pro HiFi pcm512x-hifi-0 [HiFiBerry DAC+ Pro HiFi pcm512x-hifi-0]
Subdevices: 0/1
Subdevice #0: subdevice #0
If I playback, I get sound from the RCA’s but NOT the headphone socket. This is really annoying as the reason I picked this card was for the headphone socket.
It’s also 100% volume, the volume control in Volumio is still present but it doesn’t matter what you set it to, it makes no difference on the volume.