If there was any audio delay then (assuming playing exactly with the audio) the notes would be behind too. Perhaps the real issue is Sonar is playing/voicing the notes slightly before the measured beat. Maybe an attempt to make up for possible latency?

real issue is Sonar is playing/voicing the notes slightly before the measured beat. Maybe an attempt to make up for possible latency?
 
Yes read my post # 16.. But this is not Sonars fault, Sonar does what the Audio driver tells it to do. 
 
Interesting about the metronome timing. I never use it, I always paste in some sort of drum track, even if it's just Hi Hat's. I have never had luck trying to stay with the metronome. 
I had copied all the patterns from my 505 drum machine and there's usually one that works for the song. I guess there is supplied drum patterns and whatnot, but I never have used those. Most seem too busy. 
 

Thanks for the comments. It actually occurred to me to create a drum track and use that to record too, then delete it at the end. I will try and see if it makes a difference. At worst case then I will just suck it up and get an audio interface which itself is worth investing in anyway. Thanks again

So I've tried the following:
 
1) Purchase audio interface - the shops I visited again told me that MIDI users typically do not require audio interface. And when I insisted to still get one, the ones available do not have USD in / out for my MIDI controller (I'm using a Nektar impact ix49, which does not have MIDI in/out ports. I connect it to my desktop via a USB cable directly). So apparently audio interface isn't even a viable option for me. 
 
2) Creating a track using drum beats as metronome. I did a recording for Sonar and Cubase each again, at the same tempo, using the same keyboard, playing the same notes. For Cubase I had one note that was off sync. For Sonar I had a grand total of 10 notes off sync, out of which 5 were consecutive, making it tedious to change. I tried again, and for Cubase I had zero off sync while for Sonar I had 9! Something is really different between my recording using Sonar and Cubase..
 
Short of upgrading to Windows 10 and using WASAPI, and purchasing Cubase, is anyone able to advise on anything that can be done to mitigate this? I know I may be grasping at straws here but both available existing options cost a significant amount of money for my budget - (well, not Windows, but I don't see it as terribly worth buying solely for the WASAPI functionality - I'm perfectly fine with my Windows 8.1 otherwise) as such, would like to ensure that all the existing cheaper options are indeed exhausted before I proceed to evaluating the ones mentioned.
 
Thanks in advance again.

You obviously went into a music shop and were given bad advice. Your seeing that their stament that " Midi users don't need an audio interface" is false. Your still need the audio drivers to make your system stable and if anything for good word clock to keep everything in sync.
 
You don't need midi ports on the interface if your controller uses midi over USB.
So you need a basic interface with GOOD drivers. Order something from Sweetwater or ?.
Look at any of the Focusrite or Tascams. In the lowest price point I think those rule.
You could get by with the $99 price point wich gives you these good brands-  Focusrite Solo, Presonus, Stienberg.   The PreSonus comes with Studio One which is a good value added bonus.
 
For $149 this is my recomondation for best bang for the buck, good pre amps and it has MIDI ports. And comes with good old Sonar.
http://www.sweetwater.com/store/detail/US2X2

Thanks for the reply. Pardon the repeated questions - I've taken a look at the audio interface you recommended, together with the focusrite and presonus ones. One thing that I want to clarify - I know it is able to connect to my desktop via USB. But is it able to connect to my midi controller via USB? I see only one USB port for the tascam model. Likewise for the presonus and focusrite the description mentions it can be powered/connected to my pc via USB.

But I need an addition USB port to connect it to my controller too. Midi ports are not a requirement for me. Do such audio interfaces exist?

Im just here to verify what Johnny is saying is 100% correct.
I've seen people confuse this a lot but yes, even with a USB keyboard/controller, Doing Midi, 
a soundcard is a must if you want a correctly synched  and stable set up.
You plug in the USB Keyboard as normal and the Soundcard USB goes in another USB Port.
 
Probably not going to help that much but you might want to give the new WAASPI driver a shot.
It's aimed at Windows 10 but I did read in the EZine some users of previous windows versions "May" benefit from it.

If your midi controller can connect to your computer via USB, you do not need an interface that has midi in/out.  You can keep it connected to your computer as it is now.
 
I have a M-Audio midi controller (see sig) which connects via USB and an interface that connects via USB that doesn't have midi.  Both of these are connected to separate USB ports.  This set up works great.  

dwardzala
If your midi controller can connect to your computer via USB, you do not need an interface that has midi in/out.  You can keep it connected to your computer as it is now.
 
I have a M-Audio midi controller (see sig) which connects via USB and an interface that connects via USB that doesn't have midi.  Both of these are connected to separate USB ports.  This set up works great.  

Right on.
I do the same thing here with my M Audio Oxygen 49.
USB in 1 port, the Focusrite in the other.

First make sure Timing Offset is zero in Preferences > Audio > Sync and Caching. This setting is intended to sync playback of MIDI-driven hardware synths with audio (including soft synths), but it will affect where MIDI is laid down while recording as well because it alters the relationship between the MIDI timeline and the audio metronome.
 
If all else fails, you can use this setting to address your record timing issue. Entering a positive value will delay the audio metronome so your performance lands later in the timeline.