2004 Envoy power wire location

I'm about to install an amp ('KickAzz' brand, 2 million watts RMS X4, THD 0.000001%, S/N ratio > 200, only costs $90, for the curious) in a 2004 GMC Envoy SLT and keep the OEM radio. There's a fuse box under the second-row seat on the driver's side. There's a large 12V power wire going from the car's battery into that fuse box, maybe 2 or 4 gauge by the looks of it. That power wire connects to the fuse box by way of a very large threaded rod with a nut on it. I'm planning on installing the new amp under the right-side seat on that second row- maybe 2 feet away from said fuse box with said very large threaded rod with said nut on it. Would it be OK to connect the amp's (4 gauge) power wire to said very large threaded rod instead of running the wire 6-8 feet through the firewall to the battery?