Some soundcard digital outputs are fixed at 48KHz. When playing back normal content at 44.1KHz, they have to resample. This makes the card sound less good than one offering genuine 44.1KHz, and also opens the possibility of some resampling algorithms sounding better than others.

Of course, some reviewers, both on the internet and in widely-read magazines, are charlatans and/or the victims of charlatans, and will offer qualitative comparisons of identical streams anyway.

Peter