USB mic into Sonar 8

I always thought that you couldn't record directly into Sonar using a USB mic but my friend has just assured me that you can. Surely the quality will be rubbish?

You have an M-Audio interface which should have an ASIO driver. Better to use that and a standard mic...
 
HOWEVER, USB mic's essentially act as their own interface. They come with drivers just like your FastTrack did (or it should have). Preferably it would come with an ASIO driver but if not it should still work with Sonar whether it's using MME, WDM, etc.
 
You just need to make sure you install the driver for the mic properly and that it is connected before opening Sonar. It should show up in your "Edit > Preferences > Audio - Devices" options.
 
When you are in ASIO mode you can only use ONE ASIO device at a time so you won't be able to use the FastTrack and the USB mic at once in Sonar simultaneously if you choose ASIO as your Sonar driver setting.
 
If you choose other driver settings I think you can use multiple devices simultaneously BUT you are more likely to have performance/latency issues.
 
USB mics are generally a good option for people doing voiceovers/podcasts because they are self contained and don't need an interface. That means single track recording and you don't really want to lean on it for an editing/mixing interface. For full on music production you'd want a proper interface (which you have).
 
So I guess it would be helpful for you to post the USB mic in question and the task(s) you intend to use it for. That way the forum can help you figure out whether or not/how you can get the results you are looking for.
 
tl;dr... USB mics will totally work in Sonar but they are only "good" for certain simple tasks and need to be set up properly.
 
Cheers.