jsg
Let's say you're using a VST like Kontakt.  And let's say you create a single instrument track.  Now suppose you need 4 different instruments loaded into Kontakt, each on a separate MIDI channel.  So now you create 3 additional MIDI tracks and route them to Kontakt.  It works.  The problem is that now when you trigger the active track and play back that instrument on MIDI channel 1, all the other tracks are receiving MIDI data as their tracks will "light up".  You won't hear the other tracks, only the active track, but it's still not good monitoring practice to see signal where there is none.  This is the situation where you want to create a separate MIDI and audio track--because when you add more tracks, the signals will be discreet.  Since every software synth handles issues differently (some allow for multiple, simultaneous instruments, some don't, some allow for patch changes, some don't) it's best to decide on a case by case basis.  For those synths that are only triggering one instrument at a time, then it makes sense to use a single instrument track.
 
JG
www.jerrygerber.com

Thanks for the explanation. I was reading the thread thinking that I've done that, added additional midi tracks to a SIT, with Omnisphere and it seemed to work fine. I can see that when I decide to develop that particular idea/project further I'll want to reorganize it first. 

Today I decided to experiment a little more in this area.  Before ramping up on SONAR, I had purchased the Garritan Jazz and Big Band library for use with Finale.  The latest version of that library comes with the Aria player.  I added Aria to the VSTs synths available in SONAR.  And this has the side-benefit of including the basic orchestra voices that Garritan bundles with Finale 2012.
 
When I added Aria to my project, I had a choice of "regular" Aria or "multi" Aria.  I think this means that the regular one has a single stereo output, and you can only select "0/1" as the output for each Aria channel.  I presume this means that Aria mixed based on the MIDI channel inputs.  That all makes sense to me, as it should be a pretty efficient way to run a lot of similar instruments, and they will all dump to the same audio track.  In other words, that would be a pretty clean solution if you wanted the same effects (collectively) on all the instruments running through Aria.
 
But when I selected "Aria multiple" (and further selected the option for mono outputs), I ended up with 32 audio tracks in SONAR.  I can see that this would certainly be flexible because each of those 32 outputs could theoretically have its own effects chain.  But what a mess visually!  And it seems to me, so far at least, that lots of effects can be the enemy of a glean mix.
 
So at least I think I understand what is possible, but I an not so sure this will lead me to a better result as the master bus hits the eardrums.  I do have a 25" monitor (plus a smaller second monitor), but that doesn't seem nearly large enough to make these really complicated routing scenarios coherent.

I never have the Insert Soft Synth dialog box insert my tracks for me, for that very reason.
 
The synth I most often use for multiple instruments is Kontakt 5, and I only happen to prefer checking the box for opening the synth properties page (the Kontakt UI).
 
I then load up whatever instruments I am including in that particular instance of Kontakt, redo the Output Section routing assignments (including renaming the outputs to better match the instrument, such as Piano, Bass, etc.), and then I add only the number of audio and midi tracks needed for each instrument.  The whole process is quite speedy, and works flawlessly.  Note - I choose to limit each instance of Kontakt 5 to load 5-6 instruments)
 
I did the same thing with Battery 3, and have several projects set up with different custom kits loaded, with each kit piece routed to its own output channels, and I already have a Drums track folder with a midi track and all of the needed audio tracks already set and pre-leveled (as a starting point for any new project).  That approach REALLY saves me a bunch of time and gives me complete control over each and every kit piece, which is a dream come true over using a couple of hanging mics to capture the whole kit - from years past.
 
Anyways, hope that helps.
 
Bob Bone
 

Bob, if I may ask, what do you tick in the Insert Soft Synth options box and why? I have always used the Simple Instrument Track option (as well as the Synth Property), but a lot of what is being said on this thread makes sense. So much so that I am considering changing my methods to suit.
 
Dennis
 
 

robert_e_bone
The synth I most often use for multiple instruments is Kontakt 5, and I only happen to prefer checking the box for opening the synth properties page (the Kontakt UI).
 
I then load up whatever instruments I am including in that particular instance of Kontakt, redo the Output Section routing assignments (including renaming the outputs to better match the instrument, such as Piano, Bass, etc.), and then I add only the number of audio and midi tracks needed for each instrument.

If I understand things correctly, you can further simplify by selecting the same output channels for similar instruments -- for example, 4 separate trombone voices might be put to the same output channel, and therefore end up in a single audio track.  This would save a lot of clutter, and would be essentially the same thing as sending 4 audio channels to their own sub-mix bus.
 
Is that a reasonable scenario?

Well, I wouldn't normally choose to do that, as I would want the ability to control each trombone voice completely separately in Sonar, rather than within Kontakt.
 
For instance, you could not apply automation to individual trombone voices if you had them all combined within Kontakt to one output channel, nor could you apply any Sonar audio effects to individual trombone voices - reverb, EQ, delay, phase, etc. (you would only get to use what was in Kontakt).
 
If I had a bunch of brass instruments to deal with, I would likely load them all into a unique instance of Kontakt 5, route each instrument to its own audio output, and to corresponding audio tracks in Sonar, along with individual midi tracks, all grouped under a track folder for Brass.  That keeps everything grouped, where you could expand/collapse as needed, AND preserve complete control over all aspects of each brass instrument's sound.
 
Bob Bone
 

Bob, did you miss my question to you prior to cpalmerlees post?

While waiting for Bob, try this
 
for the equivalent of a SIT check "MIDI Source", "Synth Track Folder" and "First Synth Audio Output"
 
For multi-out synth check "MIDI Source", "Synth Track Folder" and "All Synth Outputs: Stereo"
 
For multi-out synths with mono outputs you could also use "All Synth Outputs: Mono" instead of "All Synths Outputs: Stereo"

Thanks Scook

I did miss your question, joden - sorry.
 
The options in the Insert Soft Synth dialog box are there to do some of the work for you, and which ones you use are entirely up to you.
 
As Scook posted above, to auto-generate midi/audio tracks per the scenarios he describes would work, and there is nothing wrong with setting them that way.
 
My own personal preference is to simply leave all boxes un-checked, except for the one to open the synth properties page, because for me and my brain, inserting a single midi and one or two audio tracks for a synth that I am only using 1 set of outputs for is super fast, and I would NEVER myself choose to use the ALL outputs choices, because I would invariably end up with a whole bunch of extra tracks I would have to go back and delete.
 
Also, the synth I MOST often load multiple instruments with multiple midi channels and multiple outputs is NOT properly handled anyways by any of the options - for how I use tracks.  I am referring to Kontakt 5, which is usually the synth I use that supports multiple instruments and multiple outputs.  (Battery 3 is my other one, but I already have a bunch of custom kits and customized routing assignments for that set up as project templates).  
 
So, for Kontakt 5, if I have loaded up multiple instruments for a given instance of it, then NONE of the check boxes would have it generate multiple midi tracks (I would want a separate midi track generated for each loaded instrument, and the check box choices do not support that), and NONE of the check box options would generate the precise number of audio tracks I would need, as I personally choose to limit the number of loaded instruments into a single instance of Kontakt 5 to either 5 or 6, because of some quirks in Kontakt's audio Output Section and how it displays tracks for Input assignment for audio tracks in Sonar.  
 
So, since I limit myself to 10-12 outputs, there is no check box combination that would auto-generate that precise number of audio tracks, and I would end up with manual work anyways, either adding or deleting tracks.
 
And, lastly, I don't feel like checking and removing checks each time I am inserting a synth (depending on the synth containing multiple instruments or not), I just prefer to do the track insertions manually.  I also, in ANY case, have to go manually rename each track, set panning, and for midi set channels for synths with multiple loaded instruments going to multiple midi channels, so I just do the whole thing manually, and I rarely, if ever, miss doing something, where I might if a lot of that was auto-generated.
 
Again, this is all my own preferences, and the reasons behind them.  Other folks use or do not use particular checked boxes for their approach.  My approach works for me, and is always the same - set up needed midi and audio tracks manually, to exactly match what is needed for each instance of an inserted soft synth.
 
I hope any of that helps, it is really just personal choice - the above are the choices I made, and the rationale behind them.
 
Bob Bone