so, in other words stick to a 12 volt psu for 12 volt printer.
something like this: https://www.amazon.co.uk/Constant-Vo...ds=12v+led+psu
Will probably give you a lot more power for a lot less money and all of it 12volt.

Plus one psu per printer make smore sense - particularly if you add an on/off switch to the power cable.

Having more than one printer on a single psu does seem a bit dodgy to me.