Try to check whether the sound is come from "Relay"?
Normally relay will have "pak" sound when switching.... good quality relay should have lower/less sound....
If sound come from speaker then shld be other problem not sound from "relay".
Hope other expert here can help u...as i do not hav experience in this.
By the way your CDP is brand new or 2nd hand which had been modified before? If not mistaken some people will bypass muting transistor in the CDP to obtain better sound, the side effect is that it will have some sound during each switching.
