For using that many fans, I would recommend a fan controller. A splitter will work yeh, but you'll have so many cables going round the place it'll just be a mess.
Most 3 pin fan controllers let you turn off the fans completely, as well as control the speeds - obviously...
Just depends how advanced you want it to be - ie Do you want a touch screen? Or just simple with no screen at all or what?
I currently have an NZXT Sentry 2 which does a perfect job for me, and it has long cables so you can easily connect your fans wherever they are. Dont know if you'd feel the same about spending £30 on a fan controller though?
If you go to:
http://www.specialte...rs-cid-662.html
You cant really go wrong with any of them tbh, they're all just basically voltage resistors that slow the fans down so they all work in the same way - you're just paying for how many channels you want (how many fans you can operate) and any optional 'gadgets' like a touch screen, or in the case of the BitFenix Hydra, internet connectivity
One thing to add about the NZXT Sentry 2 though - it has 3 pin and 4 pin molex connectors on each cable, so you can control 2 fans through each channel without the need for any adapters.
Hope this helps