Followed @Nice Monkey's suggestion here and replaced my rather noisy HGST 7200rpm 8Tb with a 5Tb Seagate 2.5" HDD from an external case and used the Orico HDD conversion rack to fit it to the Z1000 Pro.
It is now virtually silent and I am very happy

The old 8Tb HDD is now in an external USB case (along with quite a few others for plugging into the Zidoo, as required).
BTW for anyone thinking the very cheap "4Tb/8Tb SSD's" from China (found on eBay and other places) are a good idea, they are certainly FAKES! There is a YouTube of someone opening one up and finding 4 dodgy flash drives wired up together, inside......