Hey gswitz,
 
I mixed down the file to wave at 41.1 and 24 bits. Unplugged the interface, shut down and restarted and the same thing happened as before, the song sounded awful. I used the audio midi auto-setup thing under the Utilities tab and chose to switch the inputs and outputs to the default ASIO driver that says my device is not connected. When I did this I couldn't hear any playback through SONAR. However I mixed the song down under the settings 41.1 and 24bits and I could listen to the file through my laptop speakers with slightly improved quality over my previous mixes, however it still was horrible sounding. I don't know if this info helps.

Just an update,
I changed the Audio Playback and Recording driver setting to MME and was able to hearing everything on SONAR. However the mix changed quite a bit and sounding exactly what I hear when I was mixing down the project, exporting it and listening to the file without my USB interface. It seems like when I was listening to the exported wave file without my usb interface I was hearing it as it sounded with the MME 32 Bit driver mode. Is there not anyway to mix the project down at the quality the USB interface provides and just listen to it in that quality no matter if I'm listening to it through the USB interface itself? It seems like I'm missing a step or mixing down and exporting improperly. I'm going to read up way more on exporting
 

I think the ASIO interface does not like many other audio interfaces at the same time.
Try and run WDM instead in Sonar, I think it allows multiple interfaces.
 
So I think your issue is to do with running two interfaces, not at all about export settings in Sonar.

There are a few points which you need to address.
 
First of all, the only time you ever dither is when going from a higher bit depth (24) to a lower one (16 bit)
Secondly, very few media players support 24 bit playback (Windows Media Player certainly doesn't) so you are correct in mixing down to 16 bit. This is when you add dither for the one and only time
 
Third, in order to test your mix, when you've exported it, re-import it back into SONAR into the same project but on it's own track and A/B between your mix and the export.
 
You can set this up quite easily.
 
First, route the export directly to your Main Outs (Interface), bypassing your Master Buss and any Fx which might be on.
Then using exclusive solo, switch between the 2. There should be zero difference in quality. If this is the case then all of your problems can be attributed to your monitoring chain, i.e. everything outside of SONAR

Hmmm thanks Bristol Jonesey, Im going to try this tonight. Thank you for the explanation! I will let you know what I find!

Also, Ifm, I have tried the wdm setting and it made everything sound quite awful again...im going to look into WDM setting more though. Thankyou.