Audio distorted in X1b but not 8.5.3

After transferring a 4-track tape recording to my computer using Sonar 8.5.3, I finally installed X1b to see how it worked. Uh, it doesn't...not with this project, anyway. Each of the 4 audio tracks have a tinny distortion on them when I open up and play the project in X1b, most noticeably on the bass and guitar tracks. Since I didn't play the project back in 8.5.3 after transferring it, I was afraid that the tracks themselves were somehow distorted from the A/D conversion (they sounded fine when I was hearing them in real time when transferring them to Sonar 8.5.3). Well, guess what...I closed X1b, opened the same project in 8.5.3, and presto--no distortion! Somehow X1b is actually creating distortion in the tracks. And it's not the crackling sound you get when the computer's resources are maxed out--it sounds like plain ol' analog audio distortion, as if the track was recorded too hot. Strange...I was wondering if anyone else has had this same problem?

I'll check the audio settings in X1. It automatically came up with the same inputs and outputs, so I assumed it was configured the same, but I didn't check all the details in the Audio settings page--thanks for the tip, Jumbi...

Setting up that rig to record again in X1 would be a hassle, so I was hoping to avoid that...

its your soundcard..most likely..you checked your audio settings??how so..like what settings are we talking here.?
the first thing you need to do is put your computer specs and your interface  type in your signiture area or give us your specs for both .8.5 might be using a different driver go in to your preference menu on the drivers tab it should say what your drivers are..just dont take for granite that 8.5 will transfer your settings over to x1..sometimes it does but things can change from your install of 8.5..new drivers,new interface.exc.your next issue is to play with buffer size..though your problem  has got soundcard written all over it its not limited to your buffer settings.read the manual on buffer sizes and check out cakewalks site for setting your soundcard preferences on the support page and tell us more and we can try and help you out.but with out knowlege of what your using for a system or hardware.were blind dude.

One cause for distortion is clipping. Check your settings in gain/trim and outs. But It would be helpful to know what the distortion sounds like.