Here is the new motor driver installed and working with the new steppers. It is the infamous 3-Axis TB6560 Chinese driver commonly found on ebay. I could have designed and built my own, but the price was too attractive to pass up. The board supports 1/16 microstepping and 3.5A per channel @ up-to 36V supply. Combined with the new motors (Minebea/Astrosyn, apparently salvaged from Diebold ATMs) the speeds have more than doubled-up, at slightly more than 200mm/s.
The enclosure (from a local supplier) is of good quality, but ultimately an overkill, and it is a bit too large for this board. Unfortunately, the nearest size in the manufacturer’s catalog was just a couple of centimeters smaller than the board.
Despite all that looks good on paper, I have to be wary of recommending this driver board, because mine turned out to be defective! Upon testing, I found out that the Y-axis was not providing enough torque. Some inspection with a multimeter revealed that the DIP-switch for the Y-axis was broken, resulting in the current setting being ignored. The fix was easy, with just a couple of wires, as in the photo above. Nevertheless, this just seems like another example of fine (!) Chinese manufacturing on display.