If the volume gets too loud from the 4 track you could damage the small surface mount input components on your card
The Mic jack is there to "Boost" passive components like microphones, guitar pickups, even turntable cartridges. LOL
The Line in jack is there to apply a smaller preamp to line level sources, like 4 tracks , cd players ,stomp boxes etc... I fried a soundcard using Mic in this is why I said Please please please!!!!!!!!
I ran the output from my Tascam 488 to Mic in and burned a crater out of the mpu on my Live Card!!!!!!
I also found that in Paltalk Playing live I dont have to use Mic in I can use Line in!!
Just make sure the creative Launcher settings are set to "Line" on the "play" side and "record" side....
Happy Recording !!!! Warmfret