I've spent the weekend putting this stuff together to make active crossing over easy. Each box has one input, 4 outputs, using the 2x4 MiniDSP kit, and a 4x100W Sure Class D amplifier with the Meanwell 24V 14A power supply. (Of course this doesn't really do 100W per channel at tolerable distortion, but with the Meanwell turned up to 28V, 70W into 4 ohms should be doable and would give >140W for the 4 woofers (driven in pairs) in each Synergy horn!). The MiniDSP is powered by a "linear" 12VDC wall-wart supply, since I have lots of those around and they give nice quiet operation and complete isolation from the AC lines. Here are the boards (assembled with feline help onto some 3/8" plywood)- Here they are after they were put inside some oak ply boxes made to make them unobtrusive (the classic "block of wood" look). I haven't used them yet, other than checking to see that the amplifiers seem to come up ok and the MiniDSP led flashes. I have to rewire the Synergy cabinets so I can bring out all the driver wires while still allowing for use with the passive crossover I came up with (and which I'm actually quite satisfied with... but the DSP crossover should be fun to play with still, and should give a flatter response -- more square waves to come!).