IMO, 4 awg in to vehicle (with a 100-150 amp inline fuse) to 8 awg to amps. a 4awg ground to 8 awg to amps as well. run the 4 to the d-blocks, then 8 to the amps. remote wire to one and either tap it or run from one amp to the other. if they are big amps, wouldn't hurt to have fuses in the d-bloks.
That would be the best way, but I would add inline fuse holders before the power distro block
mrray you didnt mention anything about rca cables.......anyways you should first check and see if your head unit has 2 sets of rca outs if not you will have to use one set of rca and in your trunk run a y-split off each plug making 1 into 2 and there you have it....