I *believe* it is also blue (real light blue), been a while since I ripped out my stock head unit and put a JVC in there though. Mine actually had a label on it that said "amp" too. Guess I was lucky.
If this problem occurred immediately after you put in the aftermarket head unit, double and triple check that those speakers are wired in right.
Once you affirm that^^, the only possibilities left are: both speakers decided to blow at the same time (not very probable), the wiring to both of them is shorting somewhere (also not probable, but stranger things have happened), or, one (or more) of the channels in your head unit is/are arcing out (which i have seen before).