[citation][nom]vmem[/nom]I think Nanoxia is the winner in this contest imho HOWEVER, I'd be curious to see how it's GPU temperature problem can be alleviated by adding a few fans, and how that affects it's noise reduction. if the overall picture is still good, then it is the clear winner[/citation]
While I don't have the Deep Silence 2 case, I have a nearly identical one - the Fractal Design Define R4. The major differences between these cases lie in the internal front panel and the hard-drive cages. The Define R4 has eight HDD bays, while the DS2 has 7. Fractal split its bays into two pieces (one holding 5 HDDs, the other holding 3), and Nanoxia installed 2x120mm fan mounts behind the HDD bays. The DS2's front panel has two 120mm fans and three 5-1/4" bays, while the Define R4 has two 140mm fans and only two 5-1/4" bays.
I placed two BitFenix Spectre Pro 140mm fans in the front fan bays of my Define R4, and moved the stock Fractal Silent Series R2 140mm fan to the bottom position (all intake). I also turned the top drive bay (the 5-drive portion) 90-degrees and removed all the unused HDD mounting trays. Doing so allows for direct airflow to the GPU and CPU from the front fans. I now have roughly 160CFM more airflow available at maximum fan speed, and internal load temps have decreased since the change. The difference in temps now versus the stocl config varies with fan speed since the fans are on the 5V/7V/12V controller, but ranges from 4-10C overall at load.
While the BitFenix fans are slightly louder than the Fractal fans, they push 20CFM more air (each) at max speed, and the noise difference is only slight. It's not the fan that's actually audible, though, but the "whoosh" of air. My advice concerning the DS2 would be to add a quiet 140mm bottom intake fan. Doing so would allow for some direct airflow to assist with GPU cooling, and should prove only barely audible.
If I have one complaint about these two cases, it's the lack of strength in the top-panel. There's simply too much flex in it, which I found out while picking it up by the top panel during the build. Luckily, it wasn't loaded full of components yet, but I could feel it flex under its own weight. (This is why I turned the 5-drive HDD bay 90-degrees rather than remove it completely. I hoped this would give the system with a little more physical strength/stability.) I've had cases in the past I could sit or even stand on, and they wouldn't give at all. (I weigh 175 lbs.) If I sat or stood on my Define R4, it would bend to a breaking point.