Thread: how much power

What that diagram is telling you is that 3 8 ohm speakers wired in parallel will present a 2.7 ohm load to the amp.
You don't say at what ohm level the amp is rated at 900 watts.
If it is 4 ohms, then the output power will probably be somewhat higher than 900 watts, closer to the 2 ohm rating of the amp.

If you wired the speakers in series, then the amp would see a 24 ohm load.

Dean

If the amp is rated at 900WRMS at 2ohms, then yes the subs would see 300 watts each. If your amp rating is at 4ohms, then it would likely make about 1200 watts rms at 2ohms, provided that the amp in question is in fact 2ohm stable. Then your subs would see about 400 watts each. If it was me I would never purchase subs with 8ohm coils for a car system. Get 4ohm coils if they are single voice coil, or 2 ohm if they are dual voice coil. This will provide the best possible configuration for most applications. As for bass amps, look for an amp that is stable at 1ohm, this will provide a sturdy foundation for any application.