What?? You want clean and airy sounding and you did a comparison with 'Wicked Game' ? Something isn't right here. That track is the musical equivalent to a TV commercial. Crushed to death victim of the loudness wars. The master sounds just like an MP3. How do expect to tell the difference? I have the same sound board you refer to in my DAW. The biggest difference is the PC noise floor. Not there with X3. Are you using the 'X-Fi Crystalizer'? Could make a difference.
Also X3 has the superior DAC. X5 uses a dated TI unit that even the mfg. no longer supports. Go figure.
Try making a comparison with a true purist engineered track. A new listening experience maybe, but if your heading for Hi Def lossless audio it may change.
I really liked the X3, but disagree that the DAC is superior to the TI implementation in the X5. Many people who have gone from X3 to X5 have found the exact same thing and prefer the X5. However YMMV, sound sig preference and all that.