Last year I had about 2500 smart pixels and my yard was like daylight. It could have been half as bright and it still would have been a fine show. The pixels we buy are designed for daylight viewing, so they have to be really bright. For us night time folks, not so much.
If you look at the gamma curve for pixels, you get the following ratio’s.
75% power – 14% drop in brightness
66% power – 17% drop in brightness
50% power – 27% drop in brightness
25% power – 47% drop in brightness
Last year I ran my lights at 90%, and in 2014 it was at 66%. So two years ago, I cut my power by about a third. I would not recommend going much below 50%, since as you drop the power it reduces the number of effective bits. To reduce the output brightness in Xlights, select models and then dimming curves for each model as shown in the two pictures. I recommend using a 17% drop in brightness.
If you do choose to reduce the maximum brightness, please check the common colors you use to ensure the shade is correct.
The interesting part about this is that at 1/2 to 1/4 current you could drive many more lights off much smaller power supplies without the need for power injection. I am surprised that nobody has thought of ordering custom WS2811 pixels with lower maximum current.