First, a comment about the audio apps you might be using. Pipe everything in to Ardour busses (and disconnect their default jack connections) so you can mix everything in one location. The Ardour mixer is much more powerful than anything else - automation for example.
With that in mind, there’s basically three things to think about:
(1) hardware inputs - you’ll find these in the list of qjackctl system inputs; sometimes more qjackctl system inputs are listed than actually exist on the interface - just ignore them
(2) hardware outputs - these are not qjackctl system outputs
(3) pcm audio streams - the qjackctl system outputs
Think of the Saffire mixer as a “hardware” mixer which lives in the soundcard. It’s sole concern is to decide what gets sent to which hardware outputs from the available list of hardware inputs and software audio streams. All the real mixing will be done in Ardour.
[Audio Software eg Ardour] --> jack system outs --> soundcard & mixer --> hardware outs
hardware ins --> soundcard & mixer --> hardware outs
Note that a soundcard monitor mixer has no effect on the recording chain:
hardware ins --> jack system ins --> audio software
You can send hardware inputs to hardware outputs (eg to insert an FX unit whose output is then plugged in to another set of hardware inputs) but mainly you’ll be trying to set up monitor mixes, and the main monitor mix is simply the left and right Ardour master outs. These should be hooked up to qjacktl system outs 1&2 (but check…).
The next part I’m not 100% sure but I think the Saffire mixer calls the software audio streams (qjacktl system outs) DAW 1, DAW 2, etc. If that’s correct, you just need to send the DAW 1 and DAW 2 to whatever outputs you want to listen on.
If a pan control is provided you’ll need to pan each channel hard left and right in the soundcard mixer.
The Saffire mixer has a bunch of tabs to set up multiple monitor mixes but just ignore that for now, at least until you get one working.