Power
delivery is often more important than actual power
rating, too. Most power specs are measured at 1KHz. That can be especially tricky with dynamic drivers. A dynamic driver is essentially an inductor, and inductors increase their load on a circuit as frequency increases. There is also increased physical resistance for a dynamic driver near its resonant frequency (which usually lands somewhere in the 60-100Hz range). So dynamic drivers often need
more power in the high and low frequencies but many amps, especially budget amps, can't ramp up the power to meet the needs. Planar drivers (like Arya) present a much different load. Their impedance is nearly constant, and often quite low, so they draw more current from an amp. This current draw often puts more demand on the amp's power supply, which often means the more robust the power supply the better the amp will handle a planar driver, regardless of its rated power spec. But, there is a lot of design that goes into it as well. For example, the Geshelli Labs Archel 2 GMR has a 12V, 0.5A power supply, which as
@Ripper2860 points out above, gives it 6 watts of power to work with to do
all its things. Amps are not 100% efficient so not all of that 6 watts can be delivered to the drivers. However, the GMR sounds much more in-control and authoritative in the low end than the iFi Zen CAN rated at 1.6W at 32 ohm and with a 5V/2.5A PSU (12.5W available). The GMR
delivers the power more efficiently and effectively.
