ValveTime.co.uk | Valve News, Forums, Steam

I just bought a 1/4" to sterio mini converter so I can plug my bass into my computer and play with mp3s and mess around with stuff.

The volume isn't very loud though and I have to turn my speakers up to hear it good, and that makes my music very loud.
Do any of you guys know of a good, and preferably free, audio mixer that I can download and pump up the volume on the line-in?
I want it to make some different sound presets to play my bass with as well.

Thanks.