Creative haven't made anything that good in awhile IMO - and I've even become a bit disenchanted with my X-Fi since bypassing the stock op amps and realising how muddy sounding they actually are :S
EDIT: Looks like the default OP AMP on those boards is the 2134? I've been playing with one of those family on my recent experiments and its a very plain sounding op amp - stick the OPA2111KP in there if you have the kit and you should have a far more lively sound. (Infact the 2134 is the "audio" version of the 2132 I've been playing with and is infact a de-rated chip with worse sound quality than the 2132 even - I would strongly recommend anyone using that sound hardware with the rear ports looks into replacing the op amp the stock one is very stable but also very unremarkable sounding almost to the point of dulling the sound).
(If your using the front panel headphone amp that doesn't apply).