In fact, each opinion about the power wire is right but not foregoing the use of fuses. The fuses are not to sell you crap you don't need (like capacitors). They serve 2 very valuable functions.
Take my case in point. My wife's car is a 2004, 645ci convertible, BMW with the top-hi/fi and Logic7. There is a design defect with the drains for the convertible top, and it caused rain water to hit the Logic7 amp. Did not fry the amp, but it did fry several speakers until I found the problem.
Rather than go with the stock speakers that were as!#nine expensive, I opted for aftermarket. Skipping the story of the nightmare of installing aftermarket amps downstream of the Logic7, I upgraded the big three. The audio system was only one reason. This car has another problem that causes premature alternator death. It already has a HO alternator, but the battery is in the trunk, and BMW only used an ~4 gauge wire to run 15 or so feet of power wire from the engine compartment to the trunk. Upgrading to 1/0 has fixed this problem. By the way, don't call a gasoline powered power plant a motor. The only power plant that is a motor is one that runs on electricity. Everything else is an engine. If a mechanic or installer calls a non-electrical a motor, run away.
Anyway, the car has a three way junction connecting the alternator, starter and power running to the battery. Although I fused the 1/0 in the trunk, I did not fuse it in the engine compartment. I used a standard three way car audio distribution block by a well known manufacturer to join the three wires under the hood. The wire running to the trunk sat on one of the 1/2 inch or so bracing **** sticking up from the strut assembly. Over 6 months, it wore a hole through the shrink wrap at the junction. Eventually, the car's warning and various other gauges went nuckinfuts and killed the engine. After AAA towed it home, I identified that the short melted the plastic cover on the distribution block and burned the power wires in all three directions. Yes, we were lucky the car did not burn. I could be wrong, but I believe why the 200 amp fuse in the trunk did not blow is because the short draws constant voltage.
Anyway, I redesigned the distribution block using a home electrical junc. box that will not allow the metal, even if the shrink wrap develops a hole, to touch bare metal, and I installed a fuse at this location.
Anyone that does not use a fuse on each power line, including to the amp(s), is asking for trouble. If you develop a short of any kind, it can fry various components in your system and start a fire. A well known car audio dealership here in Houston was sued because the installer did not properly fuse and install the power line, and the customer's car burned to the ground, along with his garage and home. Oooops. Wonder if the installer got fired?
In my case, the fuse did not blow, but the short had, by some miracle, not sparked a fire. Why tempt fate. Think safety first.
