anyone analog summing with sonar x3; if so how

Yep, I sum to an SSL. Here's what I do:
Bus similar tracks, then set the busses to outputs on your converters that go to your summing device/mixer/whatever. In my case it's usually Vox to st.1, Drums to st.2 and so on. Do not send anything to you master bus (the one that outputs to your speakers).
 
Route the output of the summing device back into a stereo input pair on your converters.
 
Create a track in Sonar and set its input to whatever inputs you just used for the output of your summing device. This track should have it's output set to your Master bus (the one that outputs to your speakers). This is the only track that should go there. I usually call it my "Print" track.
 
Enable input monitoring on that "Print" track. This should allow you to hear whatever is coming out of your summing device. Lots of folks will put effects on this track also...compression, limiting and EQ are pretty common.
 
Good luck

Dean

I would add that you need to have really top notch (read expensive as all get out) equipment to get any benefit to summing in an external hardware. I would really love an opportunity to work with some top end gear like that but for me I'm content to do most everything in the box.

I think the craze for analog summing probably comes from the fact many professional mixers used some form of analog summing w/ their external hardware.  If you have an ssl desk or old neve, you'd be crazy not to use it.  But even smaller setups started using small and line mixers as breakout boxes to incorporate their external hardware.  If you spent good money on preamps and comps to get that "sound" going in, why not use the same when mixing down?  Why use a digtial equivelant of an 1176 on the bass when you have the hardware sitting right there?
 
While there may be some small advantage to merely mixing in analog, the payoff is expedential when you add good hardware into the mix (pun intended).  And once the industry started doing this, bare bones summing mixers started being designed and sold.  Notice most of them are "clean" not character summers, since you are expected to add your own character, as well as being cheaper to make.
 
Most mixers do stems or subs to their hardware, but some people divide up the spectrum, too, so they send the low signals to one external box, highs to another, etc.  Hardware parellel compression also became a more common technique.
 
If you want to get into summing w/o expensive external hardware that is fine.  As Dean sez just breakout subs from SONAR into however many outputs your interface has and run them into a mixer w/ everything set flat so you can use automation from SONAR.
 
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