Hi audio007,
[ 6.376763] snd-rpi-hifiberry-dacplus sound: ASoC: CPU DAI (null) not registered
[ 6.376790] snd-rpi-hifiberry-dacplus sound: snd_soc_register_card() failed: -517
[ 6.380803] snd-rpi-hifiberry-dacplus sound: ASoC: CODEC DAI pcm512x-hifi not registered
[ 6.380828] snd-rpi-hifiberry-dacplus sound: snd_soc_register_card() failed: -517
[ 6.560537] pcm512x 1-004d: Failed to reset device: -5
[ 6.560665] pcm512x: probe of 1-004d failed with error -5
I understand that config.txt needs the DAC+ line to have its remark '#' removed and then rebooted.
Is this we only change you made? Please check this again.
#dtparam=i2c_arm=on
#dtparam=i2c_vc=on
#dtparam=i2s=on
#dtparam=spi=on
#dtparam=act_led_trigger=mmc
#dtdebug=on
#dtparam=uart1=off
#dtoverlay=pi3-disable-bt-overlay
# Uncomment one of these lines to enable an audio interface
#dtoverlay=hifiberry-dac
dtoverlay=hifiberry-dacplus
#dtoverlay=hifiberry-digi
#dtoverlay=hifiberry-amp
#dtoverlay=iqaudio-dac
#dtoverlay=iqaudio-dacplus
Frank