You could always apply noise cancelling foam they use in recording rooms any what not. Tear the walls down, insulate it with foam insulation, or line the entire room with Reflectix should also lower the noise down a bit. Always best to have a fan hanging from a chain or wire instead of actually mounted to something.
lol if I tore the wall down there I could probably see straight into next door
my flat is only one room wide with a hallway separating one side so I need to be as quiet as possible, I've heard some people claim they got their TD-silent quieter than their PC and my comp is pretty noisy (big ass lian li full size tower with 6x 100mm fans) so I need something about as quiet as a fridge/freezer and TD-silent seems my only option.
the separating walls must be the thinnest I've ever experienced, I can hear even when next door flick a switch on the wall or cough , although I can't hear them talking and if they have a TV on I can only hear it if i put my ear to the wall.
I can't see how anyone could ever get true stealth with a ruck I could hear it even from my living when it was at 40%, I've got a DS60II at the minute but want to move to a growdrobe for ultimate stealth at some point for when I have visitors or my 8year old son over.
As I said even without the controller the ruck still hummed loudly until it got up to about 80% speed and sounded like a mini turbine so even a variac wouldn't have helped to quiet it down