transformer rated at 50v ac, once rectified will provide ~70v DC (with no load), is this not a little high given the geckodrive guidance is 32 x SQRT (L), where L is in mH.... [32xSQRT(3.2) = 57v]

there is also another bit of guidance that says, no more than 20 x the stepper DC rated voltage (4.2A x 0.65 Ohms = 2.73v; 2.7v x 20 = ~54v), or no more than 25x the dc rated voltage or the steppers would overheat at standstill.

I am aware of ripple voltage will have onto the power supply when under current draw (hence interested to know what the caps are in the AM882H's)...

other than cost... what would be the problem with a 1000VA transformer, inrush on a 13A fused plugtop on a 32A ringmain should not be an issue, and if it was, I could always use a solid state relay which would then allow for switching only a the crossover voltage.

I got the 42V switch mode PSU, and although the nameplate says 720W (17A), it should really be able to deal with 4 stepper motors really, or at least just about (hence I was going to put one of the axis on another switchmode PSU), but it just seems to be like putting a plaster on the problem instead of getting the right power supply (a toroidal transformer) with a fair bit of design margin.

Lets face it, I have a welder that is 200A rated for 6mm mild steel, but only ever tend to use it at ~110A on 2 and 3mm plate, is it really that detrimental having a bit of margin in components? [ok, it is inverter driven, digital controlled... semi-synergic...]

Interesting in that I thought the guidance would come on voltage choice and not a VA rating discussion... as I could not make my mind up if 50V or 55V would be right for the steppers and drives or whether I was over rating it and should have been looking at 45v transformer output rating, given the no load DC voltage would be about 63V.