clicking while paused

I’m running Volumio 2.031 on a Raspberry Pi 3. I’m using the I2S signals from the Pi’s GPIO to an outboard DAC.

This DAC is based on an SRC4192 up sampling chip followed by a PCM1794 DAC.

When the track is paused I am getting a constant low level clicking noise from the DAC. This goes away when I resume playback.

Has anyone else experienced this behaviour?