Will the JBL CS60.4 four-channel amplifier with 4x60W RMS @ 4ohms be sufficient for the front Infinity Reference comps (90W RMS) and the rear Alpine S-series coax (40 W RMS)?
I also thought about that. But I would not want to leave the rear speakers without amplification. I want the people sitting at the back of the car to also enjoy the music.
If I don't play the music too loud, would it be okay to underpower the Infinity's?
Kind a like speed limits. If it says 45 MPH speed limit, that means that you can drive up to 45 MPH. It is not a goal, or a starting point (lol).
Most stock car systems run under 15 watts to each speaker. Go figure. yeah they are paper cones and they are lighter therefore require less energy to reach maximum output, but never the less, it doesnt take much to get sound output.
As long as you dont clip you stuff you will be fine.