We suspected that certain power supplies gave brighter LEDs than others, so while building a Lotto sign for a signwriter, we conducted some tests:

More than 20m of strip was used, and some pieces were close to the power input while other pieces were at the end of long runs (see low volt figures)

The results for various power supplies in table below:

Power supply Lux @ 1.7m Low volts High volts Current (A)
3A 239 10.74 11.36 3.1 (overload!)
5A 290 11.05 11.76 3.28
7A 355 11.49 12.01 3.49
10A 356 11.5 12.03 3.5

As you can see, the 7A supply gave a far superior result, while upgrading to the 10A gave a negligable improvement. This test also highlights the danger in maxing out a power supplies rating. The difference in brightness between the low and high volt ends was noticable with the 3A, but not with the 7A.

Don't skimp! A few bucks saved using a smaller power supply may cost you a significant amount of brightness!