How much do you have to spend on one?
Do you want a external soundcard or DAC? The difference between the two is that a soundcard is able to process an input(mic, line in, etc.) as well as an output. A DAC will only output sound. There are plenty of USB DACs out there with great sound quality.
50-100 in that range , im looking for a soundcard for my desktop , and i supposed i wouldnt mind just a DAC