I'm sorry it comes off that way..
But there is a method to my madness. You'll find out one of these days.
Actually I may have come off a bit harsh assuming you knew what amp classes were what.
So here is a very rudimentary breakdown. Some will poke holes in this but this is just to make the explanation as simple as possible.
First lets explain amp classes.
Class A: The cleanest design. Lowest THD (total harmonic distortion) and highest S/N (signal to noise ratio). Down side is they run very hot because the MOSFETS are always switching on/off. Usually they are around 50% efficient.
Class A/B: This is the most common amp for cars cause they are cheaper to make, still very clean and quite a bit more efficient. 60-70% usually.
Class D: This is also known as a digital amp. They have high THD and low S/N and get worse the higher the frequencies go. Thats why they are reserved for sub amps. They are very efficient so they can make more power in a smaller package and don't tax the charging system. Since frequencies below 100hz have to be above 10% THD before the human ear can hear it makes them perfect for subs. They are usually 80% efficient and sometimes more then that. Without proper test equipment I can not know for sure but unless my amps are severely over-rated then they are over 80% efficient.
OK, so there is a very basic breakdown.
Now power. Assuming the charging system is at 14v then you can divide the RMS output by the voltage and get the amp draw if they were 100% efficient.
So for my sub amps for instance its 14/600=42.86 amps. If the amps were only 80% efficient then they could pull apx 50 amps each give or take.
Now if they were class A/B then they would pull around 70 amps.
Since my 4 channel amp is an A/B it pulls close to 50 amps at full tilt. That would mean if my mono blocks were A/B as well then the stereo could pull 190 amps when cranked up all the way. That is too much for a 4awg wire that is 12' long. But since they are class D if you add their draw with the 4 channel thats 132 amps at full power and that is within the abilities of 4awg wire that is pure copper with 95%+ oxygen free.
Now I never run it as loud as it can go cause that is far louder then my ears can handle and would cause permanent hearing damage. When I jam it hard I will only see 90 amp spikes and a continuous load of apx 60 amps.
I hope this helps you a bit in understanding why 4awg is perfectly fine.