@JonD I just ran a test with a project where my synth is Pianoteq with Ozone 9 in the FX  rack, and REmatrix  in the prochannel  of a bus. The midi input for the synth was set to none, the echo was off and the midi keyboard was switched off. I walked away for a while to see if a dropout might occur with no activity or midi input. Without fail it did,  an Audio Engine dropout 1.  My question is, if you  might know,  how would I use latencymon to track down the cause, as it seems to me for this sc