Copied from Aesthetix owner's manual see below:
It is normal that a slight pop may be heard when going into or coming out of Standby. This is due to the amplifier switching from high bias to low bias.
Thanks mate. One of the potential buyers acutally contacted Aesthetix regarding this and was advised that they never heard of such probem before.
I should add that I might not have the best AC in our house. Previously whenever my wife switched on the dimmable down lights I could hear a pop from the speakers. A Torus isolation transformer fixed it. However, now even with the down lights switch off I could still hear the ticking noise in the first 5 mins.
You may be right that the monos are just fine but I just feel a bit hesitant selling them if there is slightest chance that they are faulty. Just trying to be a responsible and ethical seller. But how could the noise appear and disappear on both units simutaneously? What's the chance of them becaming faulty at the same time? This is really beyond me...