Oh yes

I can actually go one better than a potentiometer as I got on Ebay and have a very swanky benchtop variable power supply. I almost feel semi-professional in not having to bodge together another solution. I didn't get it just for the LEDs but I'll be using it for that. As you say, just clip some resistors in series until I get what I want and then get the soldering iron out. That's definitely Plan A because it involves a lot less swearing at molten metal