Specs & measurements
Power output
Also called output power, watts, milliwatts
Power output is how much an amplifier can deliver into a given load, in watts for speakers or milliwatts for headphones. The figure only means something with the load stated, since the same amplifier delivers different power into 32 Ω and 300 Ω.
A headphone amplifier might offer 1 W into 32 Ω but 100 mW into 300 Ω, because high-Impedance loads need voltage and low ones need current. Compare specs at the impedance of your headphone, and remember that most listening uses a few milliwatts; the headroom matters for peaks and Dynamics.
For speakers, doubling power adds only 3 dB. Going from 50 to 100 W is a small step; Sensitivity matters more. Specs should state the load, the distortion level and whether both channels were driven, and many do not.
audiophila. shows the maker’s stated figure on product pages where one exists.