I run a bit similar setup, the MiniDSP 2×4 balanced with an ICEpower 700AS2 and 2x Seas L26ROY 10″ in sealed boxes. It works nicely, but it’s sucks to have to calibrate twice. My mains are Genelec DSP speakers, so I first calibrate those and then everything via REW. Considering getting rid of it and getting one (or two) Genelec DSP subwoofer(s) instead.
Have you already sourced the icepowers? I don’t think they sell directly to consumers. Please note that the connectors are very hard to find separately, so might make sense to buy a complete set for easy of use. Or one easy option would be the minidsp pwr-ice250 + backbox.