Pulling it apart
I instantly ripped it apart and found that the fan was rubbish and the case was just a big metal tube. The fan was easy to rip out and put in a silent fan from a PC in it.
http://www.bassybeats.co.nz/projects/droboprofs-the-quietening#sigProIdd46b2e3549
DynaMat to the rescue!
Digging through my box of random crap I found the leftover sound deadening from fitting out the Toyota’s sound system. Lined all the casing and even lifted up the front panel sticker and lined the front. The thing is almost dead silent other than when the hard drives first start up, no fan noise, no hum and no vibration.
http://www.bassybeats.co.nz/projects/droboprofs-the-quietening#sigProId5169f16900