Export Audio issue

I read in another thread that Exporting audio is purely math and does not rely on the audio interface at all.  
 
However, that raises an interesting question / observation for me...

I just got a Focusrite Scarlett 18i8. When I went to mix down in CbB, I got horrible audio. (It played just fine in the software before I mixed it down). And no, it wasn't clipping as I limited it.
 
However, at this point, I changed the buffers in the Focusrite to 1024 and Exported again and bingo. It mixed down just fine...no glitches. For fun, I put the buffers back to 128, more scratches and pops.
 
So, if this doesn't use your audio device, can anyone help me understand what is happening here?
 
I should also throw in this tidbit...Doing the same test in Studio One, there were no pops and clicks at 128 buffers. In other words, I don't have to adjust the buffers to mixdown in Studio One.
 
Also, I'm doing a "fast mixdown" in Sonar, not the "real time" mixdown. (So in other words, the default type of Export audio)

Another interesting fact...Cakewalk cannot mixdown without a soundcard.  As an experiment, I turned off my focusrite, then loaded Cakewalk and got the expected "No audio device" error.  I then did a mixdown, which APPEARED to work, but only provided a 4kb file.  So, I have a friend that did the same thing...just as a test...only he has Sonar...not the new Cakewalk.  Same exact thing happened to him.
 
So, then I tried Studio One, and after getting the same cute little no audio device errors, I went ahead and mixed down...got a full fledged file that mixed down perfectly. 
 
So, I'm not sure I agree that Cakewalk / Sonar doesn't utilize the sound card for mixdown as Noel once stated. 

Without knowing a lot about the internals of each program, I am not sure what conclusions can be drawn by these types of tests other than the DAWs are different.

You don't need an interface or even a sound card.  You just need an audio output (real or not real, can't think of another word for fake).  I have Reaper installed on the same machine as SONAR/CbB and can create a mixdown file just by selecting one of those phony outputs created by Reaper in SONAR.  Just make sure your Master output is set accordingly (not that I know you have Reaper installed too).
 
Hit back to discuss further, if desired.
 
Kind regards,
 
tecknot

The export options in Cakewalk are more comprehensive than some other DAWs. This leads to confusion for some users. One of the options for audio export is the "Source Category" which includes Tracks, Buses, Hardware Outputs, Entire Mix and Clips.
 
It sounds to me like you have Hardware Outputs selected in this field.
 
I usually bounce my mixes to a track and then export the clip.

Good catch, Base 57. Obviously, anything routed to a nonexistent device is going into the bitbucket.
 
However, the original assertion that the export does not rely on the audio interface remains valid, insofar as the interface has no bearing on what the exported audio sounds like. Whether you have a $7,500 Lavry or a $10 Realtek you'll get exactly the same results when exporting.