look into, i think Delta's, laptop/desktop external PSUs, they hit the 87-90% but they are a higher voltage DC.
There is also nothing wrong with using a PCIe power adaptor off a desktop internal PSU
Perhaps domestic drivers for LEDs would be a good choice - if they produce 12V and don't try to drive a constant current.
Will do the study. Very interesting.
12V is also not a must. We only need to adjust the chain length.
All mining devices try to draw constant current anyway, so if they try to drive constant current it's also OK.
Ignore those things, they have exposed terminals and are NOT user friendly. I don't know why they're being discussed for an introductory consumer device.