how much power do you need two drive magnpan1.6s

Magfan...True that Watts = E * I,

But I = E/R

So Watts = E * E / R.

Also, the "rail" voltages get output one at a time. PlusV-to-ground OR MinusV-to-ground. Never PlusV to MinusV.

Also, the 4 amp fuse is at 120 volts. It can yield much greater current at the lower voltage delivered to the speaker via the amplifier.

Eldartford, is this a test? Sorry, but as near as I can determine, a fuse can be used at any voltage below its rating.
In the 'hydraulic' model, volts is pressure and amps is a quantity....somewhat independent.
If your contention were true, the fuse would provide little or no protection, since you could somehow devise an amplifier which would output very low voltage @ very hi current, and still be within your definition of a fuses ratings.
A fuse doesn't dissipate 'watts'...

My bad with my first post was poor choice of numbers.
I still maintain that hi-current to maggies is somewhat of a red-herring.
Please design a scenario where a maggie can receive say...20 amps at whatever voltage you choose. Than, find me an amp that produces such and not 'pop' the fuse.
Also, with the voltage rails at +- a (given) voltage, this represents the maximum voltage the speakers can see. The absolute value of +-50 volts is 100v Without Sign. (absolute value definition)
The only thing left to argue about is 'how large a spike a fuse can take over what time period'
http://www.circuitprotection.ca/fuseology.html#Top
Link has useful chart and definitions. Go to the bottom of the page and look at 'Voltage Ratings'...that a 250v fuse can safely be used in a 125v circuit negates your arguement.

Magfan...Stop and think about what I said. Sometimes the voltage at the hot (red) terminal of your amp may be +70, and sometimes it may be -70 but the black terminal is always 0, so the speaker never sees more than 70 volts across it.

80 volts applied to a 4 ohm Maggie would result in 20 amps (assuming the amp could deliver this). The power would be 1600 watts, so it better not be applied very long!

At 120 volts 1600 watts is 13.33 amps. If course no amp is 100 percent efficient, so the 120 volt line fuse would need to be a higher value. If, however, you had an amp running on 240 volt power, 1600 watts would necessitate only 6.67 amps plus some for amp inefficiency.

4 amps at 120 volts represents 480 watts. For simplicity let's assume the amp is 100 percent efficient. If you had a speaker with a 1 ohm impedance 22 volts would be 480 watts. The current drawn would be 22 amps (and all from that 4 amp fuse in the 120 volt line).

Your remarks about fuse voltage ratings makes no sense. I never said anything about fuse voltage rating. The voltage rating exists to protect against arcing after the fuse blows which might occur if the voltage is greater than the fuse rating.

So, what is the bottom line? Are Maggies 'current hogs' or not? Doesn't seem that no matter how the numbers are tortured that you can get more than 6 or 7 amps thru them, adding 4amp mid/tweet and 3 or 4 for the low freq. Based on math we have already agreed to....E=IR gives about 50 volts. I am using 6ohms....and 8 amps. (rounded up)
Than P=E2/R gives just over 400 watts....(round down of <5%)
The reason for 6 ohms, is the 18ohm peak at 600hz and the 6ohms from 200hz to 2khz, where MUCH music power resides.
The actual musical average MAY be higher...'weighted' for frequency. This would result in a higher power requirement at 'red line'.
It appears that a good amp of upper to hi end power rating is more than adequate. Choose your presentation and have fun. Rotel? sure......Mac? no problem.......Krell yep,if you have the coin.....Bryston dream on (pant pant)

One puzzle, though.
You said:: "Also, the 4 amp fuse is at 120 volts. It can yield much greater current at the lower voltage delivered to the speaker via the amplifier."

Could you please elaborate or explain? It SEEMS to say that a fuse running at lower than rated voltage can pass more current...???

Magfan...If we use 6 ohms (as you do) I agree with your 400 watts. However, I was under the impression that MG1.6 were a pretty flat 4 ohms, and resistive to boot. Using 4 ohms and your 50 volts gives 625 watts.

A fuse blows because of I*R heating. Voltage doesn't matter. How long it takes to blow a fuse depends on how high the current is. The rating of a fuse, eg: 4 amps, is the current it will carry forever without blowing. Most fuses actually carry about 1.2 times their rating for quite a while, and twice their rating briefly. "Fast blow" and "Slow blow" fuse types are designed to modify these typical characteristics.