Generally speaking the impedance of a driver is dependant on the type of driver and manufacturer.
Large bass drivers often have an impedance dip at the lower end of their frequency response. Whatever amplifier you use, it must be able to drive the chosen driver at it's minumum impedance. The power needed depends on the efficiency of the driver and to some extent the cabinet configuration the driver is mounted in.
Mid-range and tweeter drivers may also have a low impedance (compared to 8 ohms) but are often more efficient and need less amplifier power to produce a given SPL. So generally speaking, the amps driving these speakers do not have to have the same power levels as the bass amp. That said, you may still want very fast (high slew rate) amplifiers for the mids and tweeters, and often high slew rates go hand in hand with high current output capability.
Large bass drivers often have an impedance dip at the lower end of their frequency response. Whatever amplifier you use, it must be able to drive the chosen driver at it's minumum impedance. The power needed depends on the efficiency of the driver and to some extent the cabinet configuration the driver is mounted in.
Mid-range and tweeter drivers may also have a low impedance (compared to 8 ohms) but are often more efficient and need less amplifier power to produce a given SPL. So generally speaking, the amps driving these speakers do not have to have the same power levels as the bass amp. That said, you may still want very fast (high slew rate) amplifiers for the mids and tweeters, and often high slew rates go hand in hand with high current output capability.