i know i can use the d-block to share the power cable, and y-adapter for rca, but how about ground and remote start? what can i use to share them??

 

Ground can be also shared with the first ground (same hole) or make another. The remote wire can just be butt connected (2 into 1) together and then go to each amp, or just jumped from one to another.

--Don

BTW, if your HU has more than one set of preouts then run another set of RCAs rather than Y-splitters, they cut your signal down.