Thank you, sir. Drawing below is about right? Will be using 14 gauge for REM wire. please feel free to add any suggestions.That 3.5A is the current draw for the amplifier simply being turned on. That is not being pulled from the remote wire of the DSP. I don't see remote current draw in the specs you listed, but guestimating it's probably less than 100mA. The 500mA remote line of the DSP can probably handle the 4 amps, but if it were me, I personally would go ahead and do a relay. In addition, I would also stick a 500mA fuse on the remote out of the DSP. The fuse is cheap protection.
I was thinking about this busbar, anything better than this one?
https://www.amazon.com/Pair-Terminal-Distribution-BUSBARS-Terminals/dp/B07C4W7YKG/ref=sr_1_6?crid=3DBOF2ENNJ9BP&keywords=bus+bar+terminal+block+12v&qid=1670602484&sprefix=bus+bar,aps,134&sr=8-6