MikeC, when I said I wasn't chasing the absolute minimum volume I'm talking liters not dBA
Pappnaas, the Cooler Master inexplicably takes a USB3 header and wastes it by only providing one rather than two ports, it's larger than the Lian Li and the Thermaltake put together, and Anandtech wasn't impressed with its acoustics and thermals, so I'd counted it out. But since it's cheap and the extra size is primarily depth maybe it should be on the list to consider anyways.
The coolcube has no space for an optical drive. Instant disqualifier for this system.
Lian Li certainly has quite an array of mini-itx cases, but the list of those which are small, inexpensive, have the components I'm looking for, and for which I've found reviews saying the acoustics are good is smaller by far. I guess if I'd had the feedback I've had now back when the Q07b was on sale I would have grabbed it. Maybe I'll still do something like that.
After double-checking the test system setup on some of the reviews I've seen and then looking more closely at the actual power requirements of the optical drives, it seems a 120W PicoPSU (or other DC-DC PSU) may be OK. What do other people think? If it'd work, putting the AC-DC step outside of the case certainly does have its advantages.
I'm seeing a few cases from obscure manufacturers- Habey, Morex, Realan (see also ecosmartpc)- that have DC-DC PSUs built in. Ecosmartpc also sells fan+picopsu plug mounting plates to cover the gaping ATX psu hole for using the picopsu in normal cases.
In the absence of cases with built-in SD readers, I guess I could forego USB 3.0 front ports for a case that had a front 3.5" drive bay and purchase one of the USB3 card readers that gives you a USB3 front port as well. Or I could do that plus slim optical in a full size 5.25" bay with one of those adapters.
(Apex mi-008 + $25 5.25 ->slim optical & 3.5 bay adapter + $40 card reader with usb3 front port+ $70 picopsu bundle + $20 mounting plate for the picopsu lead = probably workable end result after spending $155 to overcome the inadequacies of a $45 case+poor psu)
I'm just frustrated. For two years now it's been possible to purchase small quiet nettops with built-in card readers, usb 3.0 front ports, and (of a necessity) efficient, quiet DC-DC converter+external power brick PSUs, getting the entire computer for <$200. But heaven help you if you want to get a more powerful processor and/or an optical drive, because DIY cases and PSUs seem to be stuck in the previous decade.
I was thinking of doing a similar build two years ago
and ended up deciding "hey, it's a luxury and my current PC hasn't keeled over yet, I can wait until cases catch up and better APUs come out." But now my old build really is keeling over and I don't know that things on the case side have improved much in all that time.