As long as you are only interested in having a 2 channel source, a program called Console should work great
there is also a similar program called audio mulch, but for what you currently want to do, console should be easier to use. For the record, I am finding that audio mulch does better for audio effects processing, and console is a great, but more basic version.
Basically, you would need ASIO4ALL, and console to get started- a4all would be so that you can have all the outputs you need to send Audio to, and console would be the program that you would use to send the audio to all 4outputs. To adjust the level of the signal in console, right click and hold in the middle of the 'wire' going to the output that needs adjustment, and drag down
I know this is a little confusing at first, and I am really trying NOT to write a whole book on the subject, so download asio4all, and the demo of Console, and post any questions you have on how to set it up.