If you need to make a digital copy of a protected CD via SPDIF, slave the clock of your soundcard to the SPDIF input if it is possible, it's the only way to get bit-perfect copies.
Otherwise, an asynchronous sample rate conversion is performed on the incoming data to prevent drop outs due to clock drift. It doesn't affect the sound very much, but it's better to have lossless copies.

Works with MAudio Audiophile 2496, Terratec DMX 6fire, Terratec EWX, Hoontech DSP, Echo Mia, Marian Marc2, Midiman delta DIO...

Not supported by Creative labs or Hercules soundcards.