Over the past few years, there have been many discussions about what voltage to run various brand / colour LED strings from. LEDs are current driven devices and can go from off to smoking debris with only a small increase in applied voltage. Some time ago, I flagged the pitfalls of using LED strings on power supplies of much higher capacity than what they shipped with. It's my belief that a lot of LED set manufacturers use the output impedance of the tiny plug packs to limit the LED current. Substitute a grunty PSU (with a much lower source impedance) and suddenly there's nothing to limit the LED current! The other way manufacturers limit LED current is via the thin wiring used. Once you cut off the "lead in" cable and substitute something heavier / shorter, you've removed some of the resistance they were probably counting on. LED strings really need a series resistor for each "section". This will help equalise variations in LED voltage due to temperature, colour and batch parameters. Some LED strings have these resistors inserted inline with the wiring and some don't. Anyway, just my ramblings to provoke a bit of thought and discussion.