Picoreplayer and ALSA equalizer interference

I've upgraded all my picoreplayers to the latest stable version. The main reason is for the equalizer as it makes my in-ceiling speakers come alive. However I've noticed when I apply the ALSA equalizer in the Tweaks menu and reboot, the speakers (via an HifiBerry DAC+) emit a rhythmic ticking noise. The interference disappears when I remove the ALSA equalizer. Has anyone else noticed this?

Thanks,
Mike