I downloaded the latest Volumio last week (2.163) and installed on my Raspberry Pi Zero W.
I plugged the HifiBerry DAC+,
On Volumio settings, I selected IS2 DAC "on", and Hifiberry DAC Plus
but I got no sound on the RCA outputs,
led is on while playing
if I connect via SSH, and type "aplay -l" I got:
"card 0: ALSA .......
"card 1: sndrpihifiberry [snd_rpi_hifiberry_dacplus], device 0: HiFiBerry DAC+ HiFi pcm512x-hifi-0  Subdevices: 1/1 Subdevice #0: subdevice #0"
and every time a new song starts, it says:
"pcm512x 1-004d: No SCLK, using BCLK: -2"