UR44C monitoring line in, cubase output is not working

Cool, thank you! I was trying to describe everything as clearly as I could; I’m new to this interface and my other A/D devices seem a little more simple.

Here’s a picture of the two interfaces. The FocusRite isn’t plugged in; it’s just there, and this is me basically taking the connections from the FocusRite and migrating them verbatim to the UR44C. I have since moved the monitors to the main outs on the back, but everything else the same (including what it’s doing, so that didn’t change anything that I can see.)

In this picture, the far left jack is the strat going direct in, phantom power is off; the Phones 1 is what WAS going to the monitor, those jacks are now plugged into the main 1 and 2 on the back of the UR44C, and the Phones 2 was my headphone jack. (Output is set high here; I’ve tried changing this and saw no difference.)

This (really lousy) photo is the back. Line Input is the hardware synth; MIDI is plugged in to that same synth (it’s off) and USB is plugged directly into the MacBook.

So what I prefer to do in Cubase is have multiple mono sources and use FX channels to treat them, even if the mono track is the only source for the effect, so I might have “guitar in” → “guitar amp” → Main Out. It’s partly organizational, partly a way for me to select tracks by track instead of lane, and it gives me a lot of flexibility in routing. But it means if I want to hear my “amped” sound, direct monitoring of the input track (the untreated Strat in this case) needs to NOT be running.

This is what I’m using to test this out. In this case, I am playing the Strat (just letting notes ring) when I hit the screenshot; you can see the track’s monitoring (but not armed, wasn’t recording) but the FX channel is getting nothing; likewise, Stereo 1 is getting nothing. I was hearing the untreated Strat in the headphones. I have no idea why.

THIS is dspMixFx’s configuration with that output. I have Cubase set to use the UR44C’s high precision as input, direct monitoring is ON in Cubase - because when I turn it OFF, I get this:

… that music line is SCREAMING FEEDBACK and I have no idea where it’s coming from or why.

I’m pretty sure it’s something I’m doing - others use the UR44C appropriately, from what I can tell. I just don’t know what I’m missing, and I don’t know how to describe things better than what I’m doing already.