When trying to obtain the accurate output of an amplifier (particularly brands you have never heard of that claim huge power), use this formula to figure out the true RMS rating. Calculate the total fusing on the amp (its those little fuses on the side). amps x voltage = highest continuous wattage possible. You also have to factor in the amplifier's efficiency. For a class A amplifier, 45-50 %. Class AB, 55-65%. Class D 70-95%....Here is an expample of this...

Hypothetically, I had a class AB amplifier with a 20 amp fuse that claims to offer 1000 watts. I would verify this by doing the following; 20 amps x 14.4 volts = 288 continuous wattage possible. 288 watts x 60% = 173 watts. Total continuous wattage than can be offered by this amplifier, 173...

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smpl_gy running a smpl system...
one amp, one sub and 1.6 kilowatts of 50hz and below...