I tried the MA1s (bigger brother of M60) with 4 ohm speakers, including the top of the line (at the time) Dynaudio Consequence. No good.
8 ohm - yes quite good. Varying.
Spelz autoformers - I tried and was not convinced. Veils the image a bit and contradicts the OTL idea.
My current speakers have Impedance: 16 ohms nominal, stays between 13 and 17 ohms above the bass impedance peaks, and Efficiency: 92 dB/1 watt.
This is clearly health food for my Atma amps. Their sonic performance rises to new heights. But results could be suprising. If you can try with the Elipsas, great.