To add to what seth said,your mini system is not 520 watts,you should understand that 520 watts is an obscene amount of wattage & not likely to be packaged in any mini system,manufacturers rate all in one systems using simple math.
Amplifier power at 1khz = 70 watts short term peak.(real world measurement,about 15 watts).
Built in subwoofer max power handeling = 250 watts short term peak.
Left speaker max power handeling = 100 watts short term peak.
Right speaker max power handeling = 100 watts short term peak.
Add all the numbers together & the manufacturer can claim 520 watts total system power,this is not a realistic or honest way to measure or advertise wattages,just an example but you get the idea how manufacturers skew the specs to make their product look powerfull.
Real world specs would be around 15 watts for the amplifier,maybee 50 watts for the sub & around 30 watts for the speakers.