Well, it will definitely run your monitors.
It has two line outs for your monitors and then a headphone out on the front. For inputs it has 2 x XLR, and 2 x TRS. It's only two channels, so you just mix and match whichever inputs you need at a time.
When you say outboard gear, do you mean a preamp/comp or outboard effects (verbs, delays, etc.)?
You can use a preamp/comp with the duet easily. You just plug the preamps outputs into the duets inputs and select the appropriate line level setting in Maestro.
So you can run any effect IN BETWEEN the source and the duet just fine if the effect is appropriate for that signal path.
There are NO effect sends
on the duet. So if you are wanting to mix in an outboard verb with a send/return, then you need to look elsewhere. (Or get an effect that has AD/DA.)
So here's the quick breakout:
Duet CAN do this:
Duet can NOT do this: