is 40V enough for DM556?

I have a toroidal transformer with 3 isolated 28.5VAC secondary windings.

The windings can be configured to provide 28.5VAC, 57VAC, and 85.5VAC

The DM556 only accepts DC input, so I am building a rectifier (the existing one is terrible).

28.5VAC rectifies to about 40VDC

Is 40VDC enough?

Is 48VDC better?

I also have purchased 2 DM860 drivers that accept 18-80VAC.

I can power them with 57VAC. Is that enough?

Would it make sense to just buy a new 35V/70V transformer or something and then sell the old one (it's toroidal)?

Where would I buy such a transformer?

The DM556 will be fine at 57 volts AC
I have drivers rated or 65v AC and have run them at 64V and had to pay attention to other parameters as that was so close to the max.
So next time I ran them at 60v AC and then finally found the manufacturers specs which I think said 55 volts was recommended!

As far as DM556 goes, 40 volts is probably OK too. It is possible to calculate the maximum voltage to achieve specific performance. A friend developed a spreadsheet that does this. In a recent design for  2 amp Sanyo denki steppers, it only required 38 volts to achieve 60m/min rapids and 5 m/s/s accelleration on a 29kg gantry. But that was after some trial and error with gearbox ratios and pinion diameter to get to the sweet spot.
 

Ok.

My new rectifier will be finieshed tomorrow (some random capacitors from my school that everyone else forgot about and a rectifier bridge+heatsink desoldered from an iMac PSU on a proto board from Thailand).

The old rectifier used a 40V capacitor for 38VDC!
Only 2 volts away from damage!

My new rectifier uses 63V caps just in case.

6 680uF 63V capacitors

So 4080uF + the internal input filter capacitor of the DM556.

How much average amperage will 2 DM860@57VAC and a DM556@40VDC draw?

I don't want to fry my transformer!

Should I connect one transformer lead to ground (the plug is 3-prong, the chassis is grounded steel)?

Also, it's not really 40V, its more like 38.5VDC.

Diodes have voltage drop.

A full-wave rectifier drops like 1.4V

Soldering Iron or Wood Burner temps will melt skin. Had a friend when I was 9 or 10 who picked up his mum's Wood Burner Iron. Old Greg was a built different to everyone else. Pretty sure when he was working on a trawler he just pulled the tuna in with his bare hands, bet he would of tried to bite the heads off a few as well.