Ok so you have an amp that puts out 50w @4ohms.
Ohms law
P=V ²/R and V=IR
P=power, V=volts, R=resistance, I=current
We know that 50w=V²/4ohm or 200=V² or 14.1=V.
So now we know the Voltage we want to solve for the current across each channel. I=V/R or I=14.1/4 or I=3.53
So now that we know the current per channel we can plug it in to find out what the power output of combining two channels would be. P=I²R or P=7.06² * 4 or P=199.37 watts
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Ill say i go by His and Al's thoery of "Your getting sprayed" Doesnt matter what it is. Grandma in the 1982 LTD is gettin the bottle.