KLH model 9 electrostatic Speakers

Will Dynaco st 70 watt good enough power for the nines?

It will run them. But the amp, as good (as a refurbished one is) will be a bit outclassed. 

Yes, they would absorb some power but they would cost only $40 dollars and I bet you would still get 60 Watts out of the M60's. The other thing is the roll off would be way up there and I doubt most of us could hear it?

You can hear it. Its an interesting idea; if the power isn't an issue it might work.

Today You would use a High power Class A amp with a lot of heat sink or an Atma-Sphere amp.
M60's would be perfect!

How much power is the atmasphere  M60?

@

While the power of the M-60 is fine (about 60 to 80 watts) the high frequency impedance will cause the amp to sound rolled off, which it is not. To solve this a set of ZEROs (www.zeroimpedance.com) should be employed. With the ZEROs the M-60s will make more like 80 watts.