Someone posted this on KVR.  The design seems well though out.
 
http://www.newegg.com/Pro...x?Item=N82E16811352020

My Antec P180s are pretty darn quiet. 

Do you mean Antec P180, Ed? That's the case I have and yes it is nice and quiet.

I have a couple of gamer cases where you can mount 72 fans. You should hear them in an 12x10 room, ceramic tile, no drapes.  Hearing them is not a problem. 

SF_Green
Do you mean Antec P180, Ed? That's the case I have and yes it is nice and quiet.

Yep. typo. fixed.

I just bought a "Be Quiet Silent Base 600" case.  I'll be moving my existing system to that case, probably next week after I get all the parts.  I'll report back on how it works. 
 
I currently have a Corsair Carbide 500R case and its pretty good but not as quiet as I would like at times.

kitekrazy1
I have a couple of gamer cases where you can mount 72 fans.

That was worth an internet search, I just had to see it.  But I was disappointed.
I believe you mean 72mm fans ?

It's been my experience that the number and quality of fans will make more of a sound difference than your case (with maybe a few exceptions). 
 
I've used just about every make of modern case in my builds and they've all been pretty darn quiet... But I stick to the same basic cooling formula:  Good-quality cpu fan, a quiet intake fan and a quiet outtake fan.  That's it.  And, of course, I make sure there are no obstructions (ie. good airflow) in the case.  The PC sits two feet from me, and it's so quiet I always forget that it's there.
 
And now with SSDs becoming more popular, there's even less reason for all the loud case fans.... unless you live somewhere warm with no A/C....

My latest DAW has an R4 case only the light tells me it is on very very very quite.

 
Which CPU you use must make some difference as well.  Mine goes up to 130w which is pretty hot.  Graphic card may also make noise if it's got fan/s.  I keep things around 25-35 deg C.  GPU's at 39c.  Maybe it's time I blow out the fans and filters.
 
I've got the huge XL version of the case in question (Fractal Design Define XL).  Lots of room and it's quiet, but not silent.  But then I have at least four fans going all the time, at low speed.