Same output to two sound cards

Hey guys. So here's the deal:

I've got two audio devices (USB Speakers + Onboard Audio) and I want to
listen to the same sound output on both.

For example: I'm listening to a song in winamp, it should play on both
my headphones plugged into my laptop, and my usb speakers.

I've been looking for HOURS with no solution. ANY HELP APPRECIATED!
thanks.

If you are suggesting I use a Y-splitter, you've probably misunderstood
my problem.

WOOT I just found a solution.

It was a little utility named audiorepeater.exe that can be found in
the zip file of the free trial download of a program named virtual
audio cable. You can delete the other files, as this is the only one
you need.

http://software.muzychenko.net/eng/vac.html#download