It may seem counter-intuitive, but you will actually achieve greater "stereo-ness" (sense of width, depth and immersion) in a full mix by using mostly mono tracks.
 
As a general rule, only use stereo tracks when the source demands it. Some examples of where stereo tracks would be preferred:
 
- full orchestra or choir
- drum overheads
- Leslie speaker
- solo piano
- ensemble miking of acoustical instruments
 
One common source where it's not always clear which is better, mono or stereo, is synthesizers and sample libraries. That's because most soft synths and samples are stereo by default, and many synth patches rely on stereophonic modulation to make them sound wide. It's tempting to assume that 10 stereo tracks of soft synths will sound really wide and lush - but the opposite is true. Don't assume that because Zebra, Omnisphere or Massive are stereo by default that you should always use their stereo outputs. 
 

The only time I would record a mono source in stereo like guitars would be if you want a very wide stereo image and you didn't want to do any double tracking. But this only saves a minute of time because you could just bounce down a recorded mono track to stereo to get the same outcome.

I think with synths you can use a similar approach to acoustic instruments.  For example if the synth is doing a bass sound then yes it may not be a great idea to record a really wide stereo patch onto a stereo track.  You also need to investigate what effects are being used also on say a bass patch.  It may sound better with any modulation widening effects removed for example and just recorded onto a mono track. Some synths like the Juno 106 are basically mono except for one effect right at the end of the chain. But it is well worth recording the chorus effect. It is quite unique. As was the ensemble effect in the Roland JP4.
 
With synth lead sounds mono recording may also apply but then again some leads may sound killer in stereo and it may be well worth recording them that way too.
 
With mid range sounds eg pads etc then stereo options may be best for sure.  Not all synths rely on modulation effects either in order to create a wide sound.  Some use the concept of stacking say 4 or 6 (or 32 in the case of the new Kurzweils) layers in order to create the stereo imaging.  Layers are panned here there and everywhere.  (in Emulators for example individual voices/layers can be panned or modulated in pan position to create the most sublime effects)
 
It would be seriously silly to ignore an effect like this and record in mono.  You would just be missing out on a beautiful wide sound for no good reason.
 
Don't forget you can always record in stereo and use a plugin like Channel Tools to narrow things down or bring back to mono later on if you feel the need. And if things don’t sum well here then you can try manipulating the phase of one side of the stereo while summing to mono. There will be a point where L and R will sum to mono and still sound robust.
 
Like all things use your ears and judge. If a synth sound sounds magnificent in stereo, record it that way.
 
Also you can mix multiple stereo synth outputs to create huge wide effects.  What you don't do in these cases is pan every stereo synth output to hard L and hard R.  A good trick is to pan some that way but others from hard L to C and others from C to hard right. Others from 10 o'clock to 2 o'clock for example.  There are many ways to combine multiple stereo synth sources.
 

chuckebaby

Bristol_Jonesey
Outputs from a guitar processor such as a Pod will be presented as stereo so I always record to a stereo track, plus an additional DI out from the Pod to give me the option of trying something else after recording

now this ^^^^ is the way every guitar track should be done if your printing a processed signal.
however... BJ are you using a POD ? we need to talk

Yep. First generation Pod Pro rackmount
 
I record to Sonar via the Pod's balanced analog outputs, can't be bothered to think about recording digitally

Sanderxpander
There is literally no benefit to recording a mono source in "stereo" (really it's duo mono at this point) since Sonar can still feed it to any effect and make it stereo (if the effect does anything to make it stereo, that is). All you're doing is wasting disk space, speed and processing power.

there is actually some "danger" in recording a mono signal as dual mono to a stereo track ... at some point you might remember that this was actually a mono source and hit the interleave button to set it to be a mono channel and all the sudden the track will be louder by 6 dB ...
 

Sanderxpander
I think a device like the POD presents a "stereo" signal just because it is too lazy/inconvenient to switch between one channel and L/R depending on which FX are used. Anything with reverb on it will usually be stereo, dual amp mic'ing etc. But a simple patch with one amp or just a wah or phaser is definitely mono, regardless of if the POD sends you two channels.

in Sonar's audio preferences you can select whether you want to see audio interface channels also as mono inputs. when checking that you also get mono channels from POD devices.
 

Bristol_Jonesey
I record to Sonar via the Pod's balanced analog outputs, can't be bothered to think about recording digitally

me too. since I figured latency of the POD is only about 1.5 ms using the balanced XLR outs is less hassle than using SPDIF and properly syncing that ...
 
 

Hello, just came across this thread.

Simple question here... how do I create a mono audio track or softsynth track?   It seems to always default to a stereo track.
 
Thank You!

Yes, when you insert an audio track SONAR defaults to stereo. I wish that was an option.
 
However, until you actually stick in some audio, it's a simple matter to switch the track to mono. There's a mono/stereo interleave selector button in the Track Inspector. Just do it before recording anything to the track.
 
If the track's being created automatically when you insert a soft synth, and you choose the "first synth output" option, then you will also get a stereo track by default. It's easy enough to change it, though, via the track's Input dropdown list and the aforementioned interleave button.

Depending on soft synth, you may actually want stereo, since most have a truckload of internal processing that relies on a stereo output.

And many FX seem to work better with the stereo interleave button on...(or off??)  I have hit that button after an effect is used at times and the artifacts or results are disturbing at times ....scary moments with phones on at times....lol.   Anyway....I gotta get better with sticking to that habit ya mentioned Bitflip....thx.   ;o)

It's true that some effects (e.g. chorus and reverb) are stereo by nature. However, it doesn't necessarily mean that the source must be stereo.
 
You can, for example, use a stereo chorus effect on a mono track. SONAR is smart enough to recognize the stereo effect and switch the internal interleave to stereo to accommodate it. Sometimes, though, stereo effects don't handle mono input correctly, in which case you will have to set the track interleave to stereo even though it's mono data.
 
Confused yet?