The headphone jacks provides low power 65 - 100mw. Its not going to provide 50 watts of power so that blood runs out of your ears when you use it. Its also not going to work with 8 ohm speakers with no amplifier. 1.5v RMS MAX (this can drop significantly based on load and current limiting).
Most headphone amplifiers provide power between 10 mW and 2 W depending on the specific headphone being used and the design of the amplifier. Certain high power designs can provide up to 6W of power into low impedance loads, although the benefit of such power output with headphones is unclear, as the few orthodynamic headphones that have sufficiently low sensitivities to function with such power levels will reach dangerously high volume levels with such amplifiers. (Meaning you can damage your hearing permanently.)
Not 50 watts for power, but 50 ohms of resistance to the headphones.
I would think higher resistance implies more power to operate but a more complete rendering of all sounds without excessive sound pressure.
Higher resistance headphones are more expensive at around $300 list price.
Thank you for the technical info. I decided to get a USB driven Sennheiser PC 363D headset.