mixing to sound card

[SMOKINDOG]

I,m recording with a tascam 424 mk 3, I want to do the mixing to my hard drive. I going from the out put of the portastudio to my sound card, with a dual phono jack to a 1/8 stereo jack into the mic jack of my sound blaster live, (the only other input is for a dat). I'm using audiotools v 4.5 interim 8. this works ok as long as i keep the master fader fairy low when sending the signal to the sound card .
The big problem is that I end up with a mono recording. I listen to the monitor speakers on the tascam when i'm mixing and have nice stereo at this point, and i can listen to mp3 files in stereo on the pc.------HELP!!!!!!!!!