Absolutely correct, as described in the previous post from gr5!
On the other hand, a 400W / 24V power supply should be sufficient as well - although not tested.
I do not mind, using both power supplies at the same time als long as the printer doesn't stop operation.
For the moment, dual extrusion is still "experimental" and raises other problems like oozing of the 2nd nozzle, etc...
I am interested in printing solid + flexible material at the same time, as well as printing the support structure on PVA (water soluble).
From what I have seen so far, the HBK greatly improves warping.
By the way: the default Y offset of the 2nd nozzle is 21.6mm.
Currently I get better results using 22.0 mm
/Johann