How do I use 2 audio jacks simultaneously(front and rear)for 2 systems

I am trying to listen to both at the same time so i can hear double the kick in the bass you know? when i plug both in it mutes the rear and i can only hear the one jack in the front.
i have an Emachines windows 7 64 bit

Please if you have any feedback i will take it! greatly appreciated

BruteDubstep welcome to the Seven Forums.

Even if you can do that it won't double the bass. You want more bass in your sound you're either need to play around with the bass/EQ settings, or get a set of speakers/headphones that have more bass.