Hi all, I may be preaching to the choir here but in case Im not here goes:
Most stepper systems increase their high speed performance when you increase their PSU voltage.
High voltage and current linear PSUs are pricey and heavy although nice to have.
It is the case however that PC ATX or AT power supplies can be stacked in series!
Semi modern PSUs have at least 15A on their 12V rail, modern ones, (£10 new from websystems in Notts), have over 30A on their 12V!
All you have to do is make sure that for all the PSUs bar one you have isolated the black ground output wires from the case & earth pin.
This generally involves opening the PSU and insulating the board from the case with a bit of plastic. Use a multimeter on continuity mode to check if the case is still connected to the black wires on the output side.
In the past I have done this to test power a large 24V to mains inverter and it worked fine!
Switchmode PSUs need a minimum load to regulate properly so all I do is load the +5V rail with about 5ohms of high powered resisters inside the case and job done.
These PSUs can be pulled out of old machines in skips etc if your skint or bought new if you're time poor and money rich.

Full details here:
http://www.procooling.com/index.php?...s&disp=52&pg=1
and here
http://www.antennex.com/preview/archive3/powers.htm

Its quite possible to get above 60V at 30A with a stack of 5!
Im about to make a 36V at ^15A supply for my new motors so I'll post photos here.
If anyone needs advice etc then get in touch, in this thread would be best because then everyone benefits.
All the best, Jim