24-bit Crystallizer. Lets face it, even if you do own a 24-bit soundcard most of the audio content accessible to you will encoded at 16-bit, whether it is Audio CD, DVD, MP3s, FLAC, etc. That is where 24-bit Crystallizer comes in, attempting to enhance the quality of such content by remastering audio content in real-time at 24-bit, functioning something like a dynamically adjusting equalizer (Philips offered somewhat similar EQ features (QSizzle and QRumble) with the Ultimate Edge 5.1).
But can the 24-bit Crystallizer make your MP3s or CDs really sound that much better? Not exactly. Although in most cases sound will be audibly different depending on how the signal is being altered, whether it sounds better is debatable; and to some extent will depend on your speakers/headphones. Generally speaking, tracks encoded at low bitrate seem more likely to sound better than those with higher bit rates. Similarly, lower quality speakers/headphones appear to benefit more than higher quality ones.
It is certainly worth trying regardless though. The effect can be toggled On / Off on the unit, while the knob can be used to adjust the level of the effect being applied to the signal. Such customisation is certainly appreciated.
So whether you like it, loathe it or would prefer to tweak it a little, you are catered to - nor is it forced on you either. For more detailed information you may want to check Digit-Lifes follow-up, which features some frequency response tests and a detailed response from Creatives Director of Audio Research.
CMSS-3D. Or more accurately, CMSS-3D Virtual and CMSS-3D Headphone, is the latest version of Creatives multi-channel surround mixer; which features Sensaura and Aureal technology. The overall effect has improved over previous generations and I found the virtualisation to be quite good for virtual 3D positioning. It is customisable to the same level that the 24-bit Crystallizer is too, which is nice.
Personally speaking I'm more impressed with CMSS-3D than the 24-bit Crystallizer, but as with most audio matters, these things can be fairly subjective and others are likely appreciate the effect.
Comparing the X-Fi Fatal1ty FPS to the Xmod there was no appreciable difference in the 24-bit Crystallizer and CMSS-3D features in functionality, i.e. CMSS-3Ds virtualisation was no different to Xmod's CMSS-3D virtualisation. The Fatal1ty FPS of course does sound better regardless.
For music and DVD playback I used foobar2000 and WinDVD respectively. Testing was carried out using various FLAC, MP3 and M4A VBR encoded tracks - primarily from Hans Zimmer, Basil Poledouris, John Powell and David Arnold scores. DVDs used included V for Vendetta, Batman Begins and Kingdom of Heaven.
RightMark Audio Analyzer indicated Xmod's overall performance to be Very Good. It's not surprising that performance would be beneath the internal X-Fi given the price difference, but that said, Xmod is a noticeable improvement over typical integrated AC'97 audio.
As expected from the results; playback quality was nicely improved over the integrated AC'97 audio in my wife's Dell laptop, providing improved detail during playback. CMSS-3D and 24-bit Crystallizer further enhanced playback (with my wife preferring both these features enabled). Personally I quite like the wider sound stage CMSS-3D provides, though I'm still not won over by the 24-bit Crystallizer claims that it restores MP3s beyond studio quality seem quite ludicrous.
Beyond CMSS-3D and 24-bit Crystallizer adjustments on the unit; further refinements (such as an equaliser) are reliant upon the media player being used.
Overall though, the X-Fi certainly does provide improved audio performance over most integrated solutions, particularly in the case of laptops.