I’d say, especially if you’re giving DJing a try as a hobby, you made a fine choice. I’m currently doing the same, mixing on a Mixtrack with some cheap Sennheiser headphones. I’m using this 2 dollar USB sound card to play my headphones off of, and it gets the job done. At first, it seemed as though the sound quality was quite low, which was to be expected, but after a short amount of time, it seems as though the card has really broken in (or at least the driver was installed properly) or something along those lines. It sounds quite crisp and allows me to cue up with ease.
Great option for someone who isn’t interested in spending another 70 bucks right away, such as myself, being a college student and all.
I’d give it a try. If it doesn’t work for you, or isn’t up to your standards, then you’re out two bucks!
http://www.amazon.com/gp/product/B000N35A0Y/ref=oh_o01_s00_i00_details