Question

There is obviously no jack out to operate a footswitch to defeat effects so how can this be done.

Answer 1

In Section 5.5.2 of the StudioLive 16.0.2 Hardware Manual, it shows how to setup MIDI CC messages to trigger volume of the FX processors on the mixer.  The Hardware manual can be found on the link below with other links to drivers and Software Reference Manuals for Universal Control.

StudioLive 16.0.2 Downloads:

http://www.presonus.com/products/StudioLive-16.0.2/downloads