I don't know about that. If the Z9 truly is a 300 Watt miner, you would not need to move too much air through it to keep it cool enough. I have an S7-LN that has been modded by sidehack to reduce the power and frequency so that you can spin the fan slower to keep the noise down. It draws ~450 Watts from the wall, and quiet enough that sitting about 3 feet away from me I can easily carry on a normal volume conversation or watch TV without cranking up the volume.
The fan is manually set to 20% which is reported as 1,680 r/min, and the reported chip temps hover in the 54-55C range. If the room is warm, the temps might climb 1-2C.
I'm considering ordering a Z9 to see how it does. Since crypto mining is a hobby for me the Z9 reaching ROI would be great. If not, well, it's no worse than blowing the engine in my race car. It will also add to my collection of miners, CPU, GPU, and ASIC, for whatever that's worth.