Great, small cases attract me more and more.
But compatibility with all motherboard form factors is priority.
Lian Li PC-Q37 for me is example nicest Mini ITX Case, but I'm sure I will not switch to Mini ITX until someone, somehow install second x1 or x4 PCI-E slot for dedicate sound card.
I have very bad speakers at home 5.1 old Creative system but very rear people who look movies and watch youtube clips not ask me how is sound so good, voice so clean...
Because 250$ worth sound card... Imagine than Audioengine A5+ connected to D1 DAC and DAC conntect to SBZXR with Optical cable...
That's reason why mATX is lowest I go and next speakers need to be active and to support as possible optical connector.
But it's much better when on table is small case with great performance than huge case with same performance.
Good PCI-E sound card and good active speakers 2 or even better 2+ central and you have impression that listen 500$ worth Bookshelf on 500$ AV Reciver.