Silent, yet great airflow. Can't decide on the case

I'll be using a regular dual slot GPU, along with a PCI sound card and a PCIe 1x capture card. I'm trying to find the smallest case with great airflow. I'm currently using a 600t, which is massive, and the mesh in front of the fans causes unbearable noise. So I'd like to get a case with fans that don't have metal blocking it like the 600t. Similar to design would be the NZXT H440, but that's a bit too big as well. 

 

Also can't decide on the mobo layout. mATX or regular ATX. I'll be upgrading my 2500k to the 4790k this summer if that's a factor at all. 

 

So far the cases I've skimmed over were the

Corsair 350D

Fractal Design Arc Mini 2

and a few others. I'd like good build quality. Metal preferably. My 600t is plastic and cracks and pops when it heats and cools. Sounds like popcorn. 

Thank you for your time.

Get a case with a lot of ventilation, remove any filters to get the best airflow possible (except the PSU filter), get at least 4 or 5 good silent fans (Noctua, Noiseblocker, Scythe, etc) and run them all on very low RPMs.

You can set your fans to create positive pressure inside the case if you are worried about dust.

A good case for this is the Fractal Design Core 3000 (about as big as the 350D, but can hold an ATX board and it's pretty cramped inside). Buy 2 Scythe Glide Stream 120mm fans, remove the front foam (I think you need to rip it off), mount one fan in the front and the other on the bottom.

EDIT: On second thought, don't pull the front foam out. Try it with it on, and with the stock fans, see if you get enough airflow and if the fans are quiet. If your computer is running too hot or too noisy, then remove the foam and start adding fans until you get it whisper quiet.

I have two SP120's from Corsair, silent series. Would these be ideal? Thanks for the input.

The SP series is meant for Radiators since they are designed for static pressure. For case fans you'll probably want fans Optimized for Airflow but you don't necessarily have to change your fans if you already got them. If you do want to upgrade you might want to look at Noctuas recently released redux series, 120mm NF-S12B for example.

With a good fan configuration, you can turn any airflow-orientated chassis into a whisper quiet machine.

Yes, they are great fans.

It doesn't matter if they are air pressure or airflow oriented, you will be running them at low speeds. Any decent fan is quiet at low speeds. And pressure oriented fans might actually do a better job than airflow fans because of obstructions in their path (like hard drive cages or metal mesh).

EDIT: contrary to the latest internet craze, I don't recommend the Noctua fans unless you have heaps of money laying around or you have all your fan mounts full of fans and you really need better fans to replace them. There's no difference between Noctua fans and Scythe fans at low speeds, and you can buy 3 Scythe Glide/Slip Stream fans for the price of one Noctua.