Can I wire a single cap to two amps without a power block or ground block?

[alex6999 10+ year member]

4 GA fuse block cost around $5 in walmart

The battery is in the trunk and it says 850A on it which I assume is 850 amps.

its cranking amp, for couple second, not working value.

I using two 250 kcmil wires(it costs me one bottle of vodka per 5 meters) connected to battery, and than connect amps with double 6GA wires.

I do not connect amp to ground, cause batterys and starter connected to ground with short 4 GA wires, i dont want overload it with future sub amp.