HELP!!

A friend and I are currently recording an album of homemade tunes and i've been using Reason to create some drum beats and synth FX.

I want to record what i've done straight into my friend's Digital 8-Track but i don't have MIDI on my PC.

I have tried using a 3.5mm jack cable to go from the headphone output on the PC to the 'track 1' input on the 8-rack which does work but the sound quality isn't great and it's only a mono signal so any panning is lost.

There is a phono or SPDIF output on the rear of the computer and have wondered about using that but don't currently have a cable which will transmit the signal at optimum sound quality level.

Is there anyone out there who can show me that way?????