There are Noctua fans in that diameter that are virtually silent.

There is so much empty space in a H9000 that it provides excellent airflow.

If you have a pro rack with active cooling it is more than enough.

Compared to an UAD Apollo or TubeOpto preamp it runs totally cool.

But the sound of the stock fans is comparable to a standard desktop PC…

Its not something you want on the table in front of you