It really depends on the quality of product you buy, and what type. I have two Infinity Beta amps putting out 2000 watts RMS alone, but there digital and I believe 80% efficient, they only draw 40amps. I use PPI amps to run the rest of the system, and with the stiffening caps on the power rails, and the PM powersupply, it really evens out the amps that it draws.. you don't get a surge from the amplifiers drawing tons of amps at once. The general rule for capacitors is the number of farads multiplied by 1000 equals the max wattage it can handle... .25f=250watts... 1f-1000watts and so on. I use (4) .5f capacitors for my sub amps... 2 for each.
