it has a digital input/output
its threw a thing called the flexi jack, which is a 3 in 1 port that acts as a digital input/output, a mic input and something else.
you change what function you want it to have via the creative software.
so if you plugged in a digital connection, you would change the flexi jack option to digital output and it would set that port for digital.
thats the way it works on my x-fi.
got the creative website and you will find out more about the flexi-jack function.
but your answer is yes it does have digital input. dont know if there is an adapter that you could get that would change from the square to the 3.5mm circle jack socket.
on the actual soundcard, its the very top port that is the flexi-jack/digital port.
from there site.
* FlexiJack (Performing a 3-in-1 function, Digital I/O1 / Line In / Microphone) via 3.50mm mini jack
* Line level out (Front / Rear / Side / Center / Subwoofer) via 3.50mm mini jacks
* AUX_IN line-level analog input via 4-pin Molex connector on card
* One AD_Link (26 pin) connector for linking to the X-Fi I/O Console (upgrade option)
the part after the Digital I/O 1 the one means this
1 Supports SPDIF Out compressed ac3 signal or PCM for Stereo Digital Speaker. Also supports SPDIF In with Creative Digital I/O Module (sold separately).