My Pete rebuild

[Waterloo]

You need two of these distribution blocks, one for ground and one for power if you are installing two amps or more. I have three amps in my truck.
https://amzn.to/2LiZFJJ

My cable, 1/0 and 4 ga
https://amzn.to/2WmRU6r

https://amzn.to/2DOIB8m

1/0 ga to the distribution blocks, ground and power, the power is fused in the battery box. This particular brand of cable is incredibly flexible, the reason I went with it. They have some nice amp kits available too if the amp(s) you are installing are not going to require some big cables. I really like these guys for their cable and lugs.

https://amzn.to/2WkkDZH

Here is the ground lug I used in the floor of the cab. http://www.onlinecarstereo.com/CarAudio/...HEEALw_wcB

The above ground lug is grounded to the frame on the underside of the sleeper via 1/0 ga cable, then 1/0 cable to ground distribution block, 4 ga out to amps, both power and ground.

Main thing is to ground and isolate the cables using the distribution blocks. Ground direct to frame if possible... Only use two isolated connections like Rawze stated. One direct power to or from battery, and one direct ground to a good surface, like the frame rail. Then distribute power and ground from there.

My home stereo is set up the same way, two outlets power everything, on their own 15 amp circuit, the AVR, 2 separate Amplifiers, one Pre-Amp and 3 subs along with the TV, BD, Cable, Turn Table, etc. The 2 amps are on one plug, then I use a power isolation strip for the rest of the stuff on the second, daisy chained. No feedback, no hum.

If that is a power inverter, I would wire that on a direct line to the battery, separate from the stereo gear. Use the heavy cable just as you would on the car stereo, run direct. Two fused power cables in, one to amp(s) one to inverter. Two grounds, use two of the ground lug posts in the floor board, I think it is easier that way than trying to run direct from battery or frame rail on the ground. That is just me. I like to keep the inverter separate from everything and ground the hell out of it. My TrippLite has two grounds.