I'm actually not switching them on and off at all. I'm leaving them at around 60%-80% brightness white, but since it's pwm, they're flashing on and off thousands of times per second. Look at it from this perspective and you'll have to agree it's the dsc - plugged directly into a 12v power supply for hours without any problems, then plugged into a DSC using that same 12v power supply and some reds (and one or two blues) flicker then burn out within minutes. That really sounds like the DSC, or the DSC in conjunction with the strings. I do realize there's nothing special about the DSC that could cause this to happen or that makes it different than any other pwm controller, but it's hard to ignore what's happening and blame it on bad nodes. If JonB256 had this problem with a different controller, then I'd blame the design of the strings.
JonB256, pm me your address and I'll send you a dsc to test. Thanks in advance for your help.
BTW, I'm up to around 9 bulbs per string out now. I just checked the voltage coming out with a multimeter and I'm getting 10.68v with my power supplies set to 11.5v using a 2ft cat5e cord. One might think that it's too low of a voltage, but if I plug it back into a power supply directly, the bad nodes don't come back on. And too low of a voltage wouldn't burn out a resistor and an led. I'm utterly confused now.