Interior Decorating

Yes, and I don't think you're going to be able to put together any system that is better than what those have built it. I am all but certain that it's technically possible, since although the ones in a decent bulb are probably pretty good, I doubt they're that close to peak efficiency. However, just using a different wall wart one with strips is at best going to be very slightly better, and you'd need a good bit of research to find a high efficiency option, and it probably would cost more for a fairly small gain. You'd be better off spending the time and money on easy, sure-shot things, like better insulation or more efficient appliances.

It would be nice if someone worked out a centralized high efficiency AC to DC converter for all the low voltage LED lights in a house, or if you could start with DC, like solar, and convert just the voltage. There's probably a decent efficiency gain with those options, but it's not something someone is going to work out for a studio.