HifiBerry not working with Rasberrry Pi 2B and Volumio 1.55

Hi there! Glad to be part of the Volumio community!

I recently purchased a Hifiberry DAC+ Pro. After connecting it up to the Pi 2 B and flashing microSD with Volumio 1.55, I cannot get the DAC+ to work. The LED lights up when the system is booted up, but turns off soon after the unit has loaded. Volumio will not play anything in the playlist as it cannot detect the DAC.

I have configured the system according to the HiFiBerry kernel 3.18 guide, using the device tree overlay for hifiberry-dacplus. The settings show up as correct in Volumio (i2s driver set to HifiBerry+).

When I run the system check supplied by HiFiBerry (./check-system.dac) the board LED lights up and the test sound plays and is audible. Then as soon as the check has finished the LED turns of and the unit doesn’t play any more audio. Running aplay -l returns the Hifiberry listing. My music library visible and I can select tracks to play from the playlist, but they simply do not play - play doesn’t progress and no audio is audible.

I first submitted this to HiFiBerry, with the response that since the system check works and the aplay is showing the HiFiBerry, it must be an issue with the Volumio settings.

I tried adding the ‘volumio’ user to the audio group since I thought it could be a root permissions issue because if I logged in via ssh to the pi with user volumio, I needed to run aplay as sudo, but not if I logged in as root. However, after adding volumio to the audio group the problem persists.

Any clues as to what is happening and how I can fix it?