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

When I had 1.6's I drove them with 250 watts they were OK but always seemed like they wanted more (which you have). My guess is the Mac is going to be fine. Like Philjolet stated they like "high current" amps (maximum output current)

whats a good HIGH CURRENT AMP

My MG1.6 sounded best when driven with a 600 watt (4 ohm) digital amp. CarverPro ZR1600. They sound almost as good with the audiophile-approved CI D200, also digital, and good for 350 watts.

Maggies can sound deceptively good with much lower power, but you won't know what you are missing.

When I had the 1.6's, I drove them with Classe' 400watt mono-blocs. That was enough juice!

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.