Where do I put it? It has a side chain jack. I had assumed I would just use it in front of the I/O for some vocal compression, but this side chain thing intrigues me. I have no understanding of what that means, but from being around here for a while, I'll find out soon.. 
 
So, I'm guessing side chain may allow me to route it most anywhere? and where would the actual cable go?

sidechaining is used to trigger the compressor for the primary input based on an input from a source which is not the primary input being compressed.
 
for example, if you wanted to sidechain your bass based on when your kick was playing, you would input your bass into the compressor, set the attack, release, ratio as you want the bass to be used, then you run a TRS cable from the bass (usually from the bass head FX send, or other alternate output) into the RNC.
 
The sidechain feature will then compress the bass when the kick triggers it, so that you get a compressed bass sound only during the kick transients allowing the kick to be prominent over the bass.

Thanks, I think I got it. Still in "grasshopper" stage.
Back to where to put it. I bought a used Tascam 4x4 for this research "project".
 
So...... mic>  RNC>  2i2>  USB port   
 
 I "think" I will use input and output 3 and 4, so as to maximize routing possibilities. Please correct me if I'm wrong.
 
The 2i2 becomes the new mobile I/O due to USB power.

mic, preamp, comp, converter.  Unless your interface has an insert send/return you can't use it w/ a built-in preamp.  Tho the 1176 etc. can directly use dynamic mics, most combos require the mic be amplified before the comp.  Sorry, there is always more to buy. 
 
The cheapest pro preamps are the ISA One and Warm Audio.  They both run about $400.  Less than that there are stand alone, transformerless mic preamps, but a better bet is getting a cheap mixer w/ inserts (or just run the output [line level] into the interface).  Old and new mixers can be had cheap and the mic preamps are basically the same as in a $100+ standalone unit, and you get a lot more functionality from a mixer.
 
@

Right - if you're trying to use the mic preamp on the 2i2, you can't use the hardware compressor before the signal goes to the computer because you can't put the compressor before the preamp, like AT says.
 
However, if you bought a Tascam 4x4, you could use it for a mic preamp as long as you're not connecting it to the computer.
 
your signal chain would be MIC>TASCAM>RNC>2i2>USB
 
just use the MIC input of the Tascam as your mic preamp, use the line OUTPUT of the Tascam into the RNC input, then output of the RNC to the LINE input of the 2i2 (don't put it in the MIC input).

NOTE:  you don't want to connect the Tascam's USB up in this configuration because you're using it only as a preamp, but you'll have to connect the power supply to the Tascam so it will have power to run the mic preamps.

I would just as soon eliminate the 2i2...but if that's what it takes, ok.
 
Mailman just dropped off the 4x4!

that preamp severely limits your routing capabilities.
 
maybe you could go xlr input channel one, out channel 1 to comp, out of comp into channel 2, channel 2 into DAW.......?
 
 
 

you may end up with a feedback loop doing it the way i described above...
 
it's possible that with your current setup,
beagles suggestion is best.
 
ultimately, to do this with one unit, you need a stereo pair of inserts on the analog Stereo Outs so a compressor could be inserted
 
 

OK that's how I  will hook it up. Actually, I'm starting to like this idea...... altho why not put the 2i2 after the RNC and use the Tascam fo my I/O?
 
MIC>TASCAM>RNC>2i2>USB
 
or MIC>2i2(ac pwrd)>RNC>TASCAM>USB?