Theoretically you could use any wire that is hot with the key on so long as it could handle the amount of current needed by the radio. The main power source for it is the switched power, which powers the stereo on when the key is in the accessory or on positions. It's a minute amount of electricity and is there so that it will remember your presets and things like that. The first is the constant power from the battery. There are actually 2 power feeds that it uses. Also had a bad connection to a door speaker that went in and out. I got a new one from the scrap yard but never installed it because it was a major PITA to run. The antenna has always been broken on my truck. The radio went out over time and if I turned it on it played the sound of the motor RPMs. One reason I got a new stereo is the stock one had some bad grounding issues. I have no idea how it detects that tiny electricity change. The new stereo I got somehow detects the moment I touch the key to the ignition and lights up.

I have a small sub I put in the extra cab floor that can be picked up and moved freely and I mounted the amp center under the dash (under the ashtray area) in front of the shifters. I know that doesn't help much but there is another data point. I installed a stereo system I bought from crutchfeild in my truck.

Ntouch radio wiring diagram