Thanks for your answer.
I think the click/crack/noise artefact occurs because the EC amplifier is a fully DC coupled amplifier and once the input relay is activated a potential DC offset on the input stage is coupled unto the speaker terminals. This is a consequence of the amplifier topology, I guess, it just doesn't sound that good. I'm just a little worried that this harmful to the speakers? However, I can then use the mute feature you mention.
I think the click/crack/noise artefact occurs because the EC amplifier is a fully DC coupled amplifier and once the input relay is activated a potential DC offset on the input stage is coupled unto the speaker terminals. This is a consequence of the amplifier topology, I guess, it just doesn't sound that good. I'm just a little worried that this harmful to the speakers? However, I can then use the mute feature you mention.