+1 on Jim's suggestion...and actually, the idea of using piles of small skiffs as a single device has a lot of potential for trouble. For one thing, that rig immediately screams "ground loops!!!". Yeah, even with DC, as the system would really need some extra ground wiring to put everything (wallwarts included) on the same groundplane and even if your power is clean, all it takes is one little grounding issue and noise WILL creep in. Or worse, let's say you have a catastrophic power supply issue in one skiff. This could easily, depending on what's misconnected or what failed, cause problems to other skiffs and their modules if something happened that allowed high-current DC onto a patch cable.
I would suggest dropping some money on a unified setup instead of this method. Fact is, a Tiptop Mantis comes in at $335, it's had LOTS of users over time with a lot of pleased synthesists, and you can join them to make a bigger 4 x 104 hp cab. And it's WAY more portable than the piecemeal one you've got currently; Tiptop even sells a custom gigbag for the Mantis. And with that, you can put together a rig with just one that you could even put on a traytable on a plane and work while you fly. That's neither advisable or viable with the current multicase build.