I don't hear a clunk on mine.
Okay, maybe a little clunk.
It's seems pretty darn quiet though.
I have customers with toilets on a second floor that buy the Aquia because they are a quieter flushing toilet then some, the water moves out more evenly and is less noticeable in the downstairs.
The water at the end, is the bowl refilling, and the water through the trapway.
Most toilets do this, you hear it on the Aquia because of the plastic trap adapter.
By the end of the week, you tend to quit listening for it.
On with the reading!