Clicking on monitor

With the latest kernel, 4.8.0, on Ubuntu 16.10, I here clicking during playback in Ardour’s monitor. Up until recently I could boot into an older kernel, 4.4.0, and playback would work fine.

Oddly, if I export the project and listen in something else, like VLC, the audio sounds fine.

I have tried this with ALSA and Jack/ALSA. I am using an older Alesis MultiMix8 FireWire.

Any ideas on how to clear this up?

Maybe it is actually clipping? Check the master-bus meter. During export Ardour normalizes the audio to 0dBFS (by default, see export-settings). Normalizing can also lower the volume.