Because moderns DACs can handle 24 bit - 192 kHz samples, some players have a chip that "upsamples" the data, such as 16 bit - 44.1 kHz samples, to higher rates. The upsampler tries to "interpolate" what the samples would have been if the original music had been sampled at the higher rate. The results are often quite good, but of course, nothing is better than having the actual music samples. DVD-A has up to 24 bit - 192 kHz samples to begin with, and the sound quality is spectacular.