Synthex wrote:A 1U case is 44 mm high.
You can put the two jack-boards in line, but the placement of inputs is not optimal ...
I couldn't put the jacks board stacked on top of each other and completely close my case. Even with the IDE cables
not connected to the board. See this photo. The jacks are slightly higher than the interior of the chassis (in the center, though the edge seems fine in the photo) even with the boards physically stacked on top of each other (read: completely touching which is probably bad for potential solder points touching the jacks below). Plus there's no room to connect the IDE cables due to the spacing between the boards (cable end is taller than the space between the boards in the photo). That might be solvable with 90 degree IDE headers but I didn't have any to try. Note this is just one chassis example, others may be slightly more spacious inside. I'd think a metal chassis would be 1-2mm more spacious than a thick plastic one.

Also, I couldn't put the boards side-by-side due to the following problems:
* I did not have an IDE cable that has enough spacing between the two connectors to be able to connect to both jacks boards side-by-side and the main board. At least using the cable I had, and the main board placement I chose. The current boards really need to be stacked vertically.
* The plastic 1U chassis has four posts on the interior to hold the top/bottom clamshell together. You can see them to the side of the jacks boards in the photo above. These were specifically in the way of the jacks boards being side-by-side. Which was more of a problem than the IDE cable issue above.
In conclusion, at least in the 1U chassis I chose which is this one:
http://www.budind.com/pdf/hb14460.pdf I simply couldn't use the current jacks boards at all.
I certainly don't fault your jacks boards, mind you. Great addition to the project for sure. I'm just sharing my issues and thoughts as a way to potentially improve the kits.
But I do think the stacked TRS jacks overall would be a good consideration as the project moves towards supporting 56 inputs. Plus it can reduce it to one jacks board, or allow them all to be soldered to the main board if you chose that option. Sounds like you're mostly considering professionally made jacks boards which would be an excellent first step.