Was about to get a toy- then I did some research...

[Neale]

The fact that the drives are rated at "20V-70V" AC in is a pretty clear indication that they are very tolerant of input voltage variations. The only thing that really worries them is input overvoltage, which is why Jazz has suggested aiming at about 10% under the nominal maximum to give a bit of headroom for the odd spike, mains surge, etc. There is no point in cleaning up the raw AC input to the drives. These devices are power switching to motors, not audio amplifiers! I hung a 'scope off the DC supply to my drivers some time ago and saw something like a 10V 100Hz ripple across the smoothing caps and the drivers clearly weren't worried about that - they've been working for a few years now quite happily. There are things that need close attention, like good earthing techniques, keeping noise-producing high power cables away from low-level sensitive feeds to inputs, but the basic supply to the drivers can be pretty crude by comparison. In fact, a simple linear power supply will beat the pants off a switched-mode supply when it comes to feeding stepper drivers as you have to drastically over-spec the SMPS to cope with the odd peak load which causes it to go into shutdown or some other protective mode where the linear supply just dips a bit and carries on.