I recently recorded a background vocal track in Sonar 8.5 Producer on my Win7 64 bit machine with a Rhode NT1A mic thru a Mackie 1402-VLZ pro mixer to a Presonus Firebox interface.  When recording the levels in Sonar looked good around -9 on the meters.  When I play it back I am getting an odd clipping type sound.  When I look at the track, in Sonar, the waveform looks like it is clipping in that it seems to be cropped at the top and bottom but the top and bottom is between -12 to -9.  When I play it back, the meters still don't show clipping but it sound like it is clipping.  This is my first real project since I wiped my hard drives and installed Win7 and re-installed Sonar Producer 8.5.  My computer used to have vista on it.  I also increased the RAM and now have 12gb of ram.  Some other random information:
Reording at sampling rate of 44100 with 24 bit depth.  ASIO mode. In audio options, I do not have 64-bit double precision engine checked, I don't recall if that used to be checked in my vista setup.  I did notice that in audio options ASIO advanced, the record latency adjustment (samples) is set to use device=creative ASIO instead of my firebox, but if I change it, it doesn't seem to stick. What should I try to fix this issue?  I am not used to having something clip when the levels aren't showing high in sonar...
Thanks,
  Andrew V. Romero

Welcome to the forum!
SONAR can not control the input level, it's done fully in your soundcard, before the signal is digitalised. You see, how could SONAR control your soundcards input level knob?

If the signal clips coming in the soundcard, then changing the level in SONAR only makes that clipped recording sound louder or quieter, it does not remove the clipping.

+1

Id check you levels in the entire chain before the DAW (the Mic, Mackie, etc...) 

Ive also noticed poor XLR connections cause this.

As above you sound like your cliping the signal before it is converted.
 
1-Set the Mackie to get a good "safe" level. A compressor inserted on the channel would be ideal.
Set the gain on the Channel so the peak light only flickers at the loudest input.
Set the master output at Unity. Observe the meters.
2- Use a line input NOT a pre amp input on your interface.
If it has a peak indicator observe it's status.
3- You need to completely disable any Soundblaster audio devices from you computer or you will have issues, this is documented over and over on this forum--Creative = Problems.
4- Make sure you have the latest ASIO drivers for Windows 7 64 bit from your interfaces web site.
5-Check the 64 bit engine

My guess would be the Mackie is overdriving the Firebox. I'm guessing the Firebox doesn't have a clipping indicator on it, but hopefully it does have an input level control. I'd do a series of test recordings until I'd found the ideal level setting. If you have to turn it way, way down to avoid clipping, then it's likely you're trying to use a microphone input with a line-level output from the Mackie. The interface may have a line/mic or instrument/mic switch; if so, set it to line/instrument.

See on the back - that is where you should first try to patch the Mackie.
I don't see that there would be a clip indicator for it but if you keep the output of the Mackie bellow unity and your track meter's in Sonar are not clipping it should be correct.
 The trick here is to try and calibrate the Mackie's output meters to match your track meters if possible.
Also I believe you have a few master output patching choices on the Mackie- Record out Main XLR and TRS? See what they show for impedance and then what the input impedance is on the line in of the interface. The sound quality will be the same, even the RCA.

If this still distorts, then use the front panel inputs and pad them down.

WTF all of a sudden I can't post any pictures?? Using IE
It shows in the pre view??

Thanks, I will play around with changing the input level on my mixer. I have just always adjusted the mixer gain/fader to the point where the sonar record meters show around -6 or a little higher. In the past I have never run into a problem where the mixer was clipping the signal before it got the interface. I am sure there are some other threads on this, but what would a decent channel compressor be?  If I buy one, it would need to be in the $200 price range.
 
Thanks,
  Andrew V. Romero

No, not the input level on the mixer. It's unlikely you can overdrive the mixer with a microphone. The mixer probably isn't clipping. The issue is more likely between the output of the mixer and the input of the audio interface.

How are you connecting the Mackie to the Firebox? Mackie Alt/34 to Firebox line-in (which is the way I would do it)? Or are you connecting some other way? Are you connecting to a regular input or connecting via XLR cable using the Mackie main outs?