i think you can, but not sure how you have the audio setup on your pc.
you might have to use the speaker/line out on the sound card for your output, and then your mic/line in on the same sound card input to darkice/shoutcast.
i used dark ice with a bct8 and other scanners without issue using line in.
Not sure if it can be done all digitally, as typically sound output from software only lets you choose outputs not inputs.
a simple 1/8 to 1/8" line cord between the two should let you output from unitrunker/sdr and input into darkice and away you go