Hello Doddy
Hmmm!!

Youv'e got me thinking about the 2x36 transformers. Do you think 2x 4700uf on each output would be enough. The Mx3660 has a wiring diagram to connect a 4th stepper. The question is would I ever need it and or would I be forever building new control boxes to upgrade. It's a holiday here in Austria which gives me some time to check this out. I'm definitely warming to the 2x36 v transformer excuse the pun.
Cheers

Andrew