My bad, the SMPS1200A400 should be OK, it just outputs 63V instead of 70/72V.
It occurred to me that many combinations of amp and power supply have been implemented, each one with different performance.
Shared PSUs in stereo amps tend to give poorer results with low impedance loads, and bigger or "dual mono" supplies tend to be better.
Amps usually have a range of allowable input voltages, and the commonly available SMPS isn't always optimum.
Sometimes a PSU upgrade can increase the output voltage as well as the output power.
For example, an NC500 or NCx500 running on an SMPS400A400 (63V) could be usefully upgraded to an SMPS1200A700 (85V) (heatsink permitting).
However you can't do the same with a Nilai500 (or Purifi 1ET400) because the max voltage is 72V, and the PSU choice is limited to the PS500DIY or possibly SMPS800RS or CONNEX SMPS2000RxE, but I'm not sure if they have the right Aux voltage.
So in practice it seems to be the PS500DIY or the PS500DIY, which is quite expensive for the power.
I was just wondering if Nilai had ever been used with anything else?