I did a bit of analog testing this morning on my speakers. 2 speaker setup first. My initial impression was, wow, the Santa Cruz does sound significantly fuller and better than the Live. So much so, that I thought something was wrong. Which in fact there was, I had the EQ enabled on the Cruz while the Live was on a fresh installation and no tweaking. Whoops. After setting everything back to the defaults, the 2 setups sounded very similar. The Cruz did have slightly crisper highs but it wasn't dramatic. Where the Cruz collected brownie points was on sound tweaking. Once again the EQ made it much easier from me to get the sound I wanted, where as the Live's bass/treble adjustments are quite crude and difficult to guage. After tweaking, the nod definitely went to the Cruz.
The 4 speaker results were pretty similar with a few differences. The Cruz does a simple channel duplication to the back and nothing else. On the otherhand, the Live does some sort of adjustment. It's kind of hard to explain w/out hearing it, but when you switch speaker setups, the sound is not a duplication there is definite change to how the music sounds. It seems like Creative made automatic "EQ" adjustments depending on what your speaker setup is. Also, at times it sounded like there was an echo. It was as if the front and rear weren't in the proper phase and the backs were a bit behind the fronts. Might be another Creative adjustment, or me just hearing things, I don't know. The ability of the Cruz to adjust F/R balance is a plus. I remember the original Live having this ability at one point, I don't know what happened to it though.
I think the Cruz does have better audio capabilities, but I think the nature of music on the computer and crappy multimedia speakers don't play to its strengths. The better your sound system, the more you realize how bad MP3's sound. CD quality MP3's, even 320kbps, are not CD quality when compared side to side with the CD. I compared a 320kbps MP3 to a superCD, and the difference was truly dramatic, there was much more going on in the SuperCD. Until a better compression/format comes around for PC's, I don't think the sound will ever really be that highend.