as of 2020 using the “HiFiBerry DAC+ Pro XLR” on raspbian using the HiFiBerry config docs

• remove dtparam=audio=on from /boot/config.txt if it exists.
• add dtoverlay=hifiberry-dacplus to /boot/config.txt

• edit /etc/asound.conf

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

• test with aplay -l

• IQaudIO Pi-DAC PRO
  • http://iqaudio.co.uk/hats/47-pi-dac-pro.html
  • https://volumio.org/product/iqaudio-pi-dac-pro/
• HiFiBerry
  • https://www.hifiberry.com/shop/bundles/hifiberry-dac-xlr-bundle/
  • (w. DAC+ PRO, RPI 3, steel case, SD card)
• various
  • JustBoom Player / OSMC / Max2Play / RuneAudio / Volumio / Moode / PiCorePlayer / PiMusicBox / OpenELEC and others / HifiBerry / IQ Audio
• BeoCreate
  • https://www.hifiberry.com/shop/beocreate/beocreate-4-channel-amplifier/
  • Up to 180W output power (2x30W, 2x60W) upto four 4-8 Ohm speakers (the two 60W channels can drive 2 Ohm speakers)
• http://moodeaudio.org/
• https://volumio.org/forum/terra-berry-dac2-review-t7871.html

list of USB/DAC supported by picore

• https://sites.google.com/site/picoreplayer/home/List-of-USB-DACs