For now I want to do it with one VST stereo output, but eventually I will want to use multiple-outs for those VSTs that support more than one.
You can record live audio from a keyboard with a single out using 'Live Input Bounce' (or at least could in 8.5) if X1 still has it available.
I'm not clear if that is what you are trying to do though.
It is also possible to redirect midi within Sonar using a Virtual Midi cable (LoopB1 is available now as a 32 or 64 bit solution) in order to record and re-route several different midi channels simultaneously through different Synths with output from MFX applied and recorded in real-time if wanted.
I've submitted a formal feature request for this functionality to be integrated ITB.
It doesn't hurt to submit your own specific request too, whether it makes any difference or not though is anybody's guess.
Here's B Rocks definitive work on Virtual Midi routing if any of this floats yer boat.
http://forum.cakewalk.com...67&mpage=1#1573767 I use it very often.