Unfortunately, the front brake is where you will notice the least difference since the cable goes through less housing than the rear.
Assuming you have the proper levers for the brake, it could be a few different simple things.
You should make sure that your housing ends are cut squarely so that the ferrule is solidly on and not moving on the housing when you pull the lever. Poorly cut housing can leave a 'fang' that acts like a spring pushing the ferrule away. When you grab the lever, the ferrule compresses back before you even begin to move the brake pads and everything will feel mushy.
Another reason could be that the cables we're not of the pre-stretched kind. They will offer a little more give at first until everything gets seated and broken in. Once that occurs, you may need to take up the slack by either a barrel adjuster or loosening the anchor bolt and pulling all the slack out.
However, if you don't have the proper lever for the Avid brake than I would start there and make sure your levers are compatible with that brake. Your levers might not be pulling enough cable.