Welcome to the forum girly stephanie..
The damping factor thing has been discussed here and there already.
For headphones above .. say 32 Ohm... it really doesn't matter that much if a driver is driven from a 0.001 Ohm power amplifier or 0.1 Ohm headphone amplifier.
It DOES when driven from an amplifier with a considerable higher output R
You see, the damping current is determined by the impedance of the driver, not by the output R of the amp as the latter is relatively too small and they are always in series for current but in parallel for voltage to make it more complicated.
The perceived 'grip' on the driver is perhaps just perceived that way or caused by voltage division FR changes.
Also note that a headphone membrane has no problems following a bass note's speed but most dynamic headphones DO have an increased impedance at those frequencies which are caused by the 'overshoot' or back EMF. Electrical damping doesn't do much though.
The toughest thing to follow are the higher frequencies.
The speed at which the membrane travels is many factors higher at 5kHz than at 50 Hz (you can do the math) yet 5kHz and even 10kHz isn't a real problem to follow.
5kHz is about the highest harmonic content of a bass and it should be noted that the amplitude there is extremely small already.
http://www.independentrecording.net/irn/resources/freqchart/main_display.htmIf it would be that problematic you would see a different impedance plots of the headphone when driven from different source resistances which is not the case.
The HEARD differences are caused by voltage division IF the output resistance is relatively big opposite the impedance and depending on the mechanical properties of the driver.
The reason the bass performance is always 'the culprit' and not have enough slam or power can (mostly) be contributed to 2 things.
Amplitude difference (due to volume control change after changing something) because of our nature of hearing (Fletcher/Munson curves say you hear relatively more lows at increased volume) and the most important factor the changes in FR at the 'bass' fundamental frequencies opposite the relatively less boosted harmonics of those bass notes resulting in a different 'bass'
An ortho's efficiency is relatively bad (little windings, relatively large airgap) and so you need heaps of power to motivate it to move.
In the other direction a motion of the membrane induces little if no current in the membrane for the same reason.... flat impedance graph.
Damping theories and 'grip on the driver' can go overboard, there isn't any grip on the membrane.
Why a power amp sounds 'better' with orthos ?... because there is more voltage and current available and thus MUCH more dynamic headroom.
Voltage isn't a real problem for desktop amps, current is often limited though.
No such limits, for headphones, exist using power amps as they are designed to deliver 10 times more current than an ortho can ever draw before bursting into flames.
The below mentioned Plinius SA-100mk2 would in fact be able to pump 20W into a T50RP which (if it were linear) would result in 141dB (if it would have survived being only 3W).
So you simply have loads of dynamic range and the noise floor of the power amp isn't bothering us due to the low efficiency of the driver.
The noise remains below the audible treshold.
More sensitive headphones connected directly to a power amp (600 Ohm headphones can be connected to power amps without any resistors) might have audible noise in the background as power amplifiers can ea
sily have higher voltage noise levels without being audible (unless our ears are close to the tweeter).
About the non-linear behavior of an electro-mechanical transducer that is most definitely a grave point.
Ruthlessly shown in Purrins measurements of the HE500 which showed the distortion is the same regardless of the amp (Magni-O2) and many factors higher than the addition of the amplifiers when using testtones.
Would be great to repeat the test with white noise and a spectrum analyser in that case the objections of single tones not revealing everything would be smaller, yet still not be the more organized audio spectrum of music.
So much tests to run but even more music to enjoy.
Though choice ... to measure or enjoy music...
In the end... an ortho fed from a power amp makes sense and has been making sense for a long time already.
