I'm developing a light display thing using a Teensy 2 and a digitally addressable LED string that draws quite a bit of power, more than can be provided over USB. I have ordered a switched wall-wart style power supply that more than adequately meets the power needs of the system, and should serve me well in production.
During firmware development however the Teensy will be connected over USB to the host computer. The methods recommended by the manufacturer are a bit invasive. I like that the Teensy is powered over USB, and I plan to keep using that function after this project is done. Also, I don't really feel comfortable taking a razor to my Teensy, let alone soldering an additional component to those tiny tiny pads.
Is it possible to power the Teensy off the USB connection and the load off a separate power supply if I make sure they share a common ground potential? Do I need to take any special precautions? Is this just a really really bad idea?
I can't shake the feeling that I should not be doing this, but I can't think of a reason why. Can anyone settle this one way or the other?