GreyArea:
Thanks for all the advice...It's a Pro Trinket...5V...apologies if I didn't mention that... (edit: I just checked, and no, I didn't...everything is 5V, I just thought it was easier that way for a novice like me).
This is a portable item, so where to connect the ground is a bit of an issue...If I connect GND on the strip to GND on the chi....sorry...board, when it's plugged into mains I assume that's okay...how does it work if plugged into a battery pack?
The point is, you want common connection points. That way, there is no length of wire that is going to cause a ∆V [which lives as noise]. Doesn't matter what kind of power source.