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

The 'hi current' thing with Maggies may be somewhat of a 'red herring'...........And I have been an owner for 25 years..starting with MG-1s...driven by a 60/side Kenwood KA-7100! I currently own 1.6s
The reason I say that is that the Maggie has a 4-amp fuse on the mid-tweeter. 4amps at even 70volts (a lot) is still 'only' 280 watts....I'll admit to nearly 2x that when adding the low frequency part of the panel.
Given a fuses response time,(pretty quick) I'd be hard pressed to justify an amp with a (claimed) 'instant' current capacity of say 40 or 50 amps. My ICE power of 250x2 at 4 ohms seems way more than enough juice, and I suspect a wattmeter will show my average use as low as a total of less than 20 watts, with an empty house and nobody to annoy with loud music.
That being said, Magnepan uses Bryston for there demos.
A 3b or 4b (SST is latest) should do the trick.

Magfan...Its Voltage squared divided by ohms load.

70 volts would be 1225 watts.

I actually made some measurements while my MG1.6 was playing very very loud music. My objective was to see if my 600 watt amp was overkill. I saw peak voltage at a level that would correspond to an amp of about 600 watts. Of course, at more moderate SPL and during most of the music the voltage peak level was more like 12 or 14 watts. Based on my findings I decided that 350 watt CI D200 amps would be OK, and I applied the ZR1600s to other tasks. By the way, my experiment was done with the Maggies seeing only 50Hz and up.

"That being said, Magnepan uses Bryston for there demos"

.....and ARC

Eldartford ...

I actually made some measurements while my MG1.6 was playing very very loud music.

How did you do this? I would love to know what my speakers are demanding during my play.

Rockadanny...I simply used a digital voltmeter, which makes a measurement about once per second. Careful observation will yield a result very near the maximum brief rms voltage. Then the peak is reasonably estimated as 1.4 times the rms. A peak-reading meter would be better, and an oscilloscope would be best.