Some cards are capable of different sample rates. 16bit/48kHz is very common, 24bit/96kHz is fairly common, and 24bit/192kHz is getting into the mainstream now. The soundcard you are getting can do the later, while your DAC can only do 16bit/44.1kHz. This is the CD standard, so you will probably be fine with that limitation. While you can get higher resolution audio files, they are uncommon and you will likely know that you are getting them.