It seems that they don’t have constant current drivers like bike lights do, so the voltage of the supply is what drives them. So you need accurate voltage, and you need to know what current is being drawn apparently.
Someone like LEDhut should be able to recommend a suitable driver, hopefully. Thanks folks.
DrP – yes, interested in the housing, thanks.
I was thinking of simply sticking them under the cabinets out of sight, and splitting two runs with a bit of wire inbetween. But that might result in a lot of voltage drop from one end to the other I fear.