[WhiteBird00]

You should do some additional diagnostic tests before replacing anything. First, make sure the amp has power and ground. Use a test light or multimeter to check for power on the two orange wires at E11 and E12 in the amp connector. Then check for good ground at the two black wires in E8 and E9. The amp connector pinout diagram is in the Monsoon FAQ sticky.

If the amp should need to be replaced, there is no need to replace the speakers or the head unit. In fact, it's safe to assume that the HU is working since you have signal to all the tweeters and they are patched into each of the four output channels from the HU.