MPC508AP as central IC on audio input selector board
However, in its datasheet, I could not find channel crosstalk and
  other audio related operating parameters and I wanted to know, if this
  IC is even suitable for audio applications?


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So that's the crosstalk but regards "other audio related operating parameters" I think you need to be much more specific. Graphs of performance cover up to 10 kHz and that implies it is for an audio applicattion but, I suspect nobody would call it top-range hiFi.