Ruark CL20 integrated recommendation?

I recently picked up a pair of Ruark CL20s. And would like a recommendation for a properly matched integrated.

6 ohm
87 db

The speakers appear to be somewhat inefficient...what minimum power do you recommend?

My considerations so far have been:
Atoll IN-100
Krell 400xi
Musical Fidelity A5...

Price range up to $2000.

Thanks
Perry