Any advice transfering a roland vs880 expanded song

[Rich b]

I've been transfering my songs to Pc using the "main out" going into the "line in" of the pc and then recording onto soundforge. Lately i've been getting some hissing on the tracks because of the low input required.
Does anyone use a roland vs880 expanded? Is it possible to use the "digital out" going into the pc? or any other ideas? I know things like echo mia are the way to go but just wondered if there were any alternatives.
Cheers