The actual thing. It has been posted on several forums, so I will consider the photographer unknown.



(sorry if this has been discussed before)

Still I believe that the voltage divider is better, perhaps mainly  because of its noise dampening properties.
And you can chose any degree of attenuation by using other resistor values, of course. I just put those in as an example. ( A higher degree of attenuation may have its advantages).

Also: People who believe in the value of the damping factor will feel more satisfaction...

(Actually I do not myself.  I always considered it a futile paper value, among other things because the current induced by the voice coil sees the resistance of the voice coil itself (has to pass through it, that is). Hence its value will be added to any "fabulously low" output impedance of an amplifier, so to speak).

All I can say is that it is very easy to confuse the (dramatic) level difference with tonal balance.
I have modified T50RP, switchable amps (0 Ohm and 120Ohm) and measuring gear at my disposal and can also compare the FR that the headphone actually puts out.
The measured differences need to exceed 0.5dB to be noticeable.

The only way to REALLY tell the difference is by measuring the FR at the headphone or by switching the 120 Ohm + increasing the amount of gain so they level match.
I learned that through experience b.t.w. it isn't a theoretical thing and have been (and continue to be) set on the wrong foot using non level matched listening tests.

Damping factor & headroom pretty much nail it. I'd also throw in low noise floor, low enough to be inaudible with IEMs with 120db sensitivity. No hum, no click & pop on input change, adequate heat dissipation, no channel imbalance on volume changes, etc. Basically a well designed amp where you don't have to worry about any hypothetical "full potential" and simply enjoy the music.

What I find odd is that so many enthusiasts have strange deeply rooted predilections about amping and often sacrifice on features, noise, etc. for the sake of some ideal design. Just ask around about an amp for the HD800 or HE6 and you'll assemble the militant factions.

Threads like this are an awesome reminder for me to give less of a fuck.

the problem here is that the question will always yield different responses depending on who you ask.
For that reason there will never be a satisfactory answer to everyone.

The main 'problem' is here that people mix up power and voltage.

Most headphones do not need a lot of power (check my table: http://www.mediafire.com/view/dzwe1g73q6pbhnx/headphone%20power%20table.pdf).
Only very few inefficient ones do and don't even need that much as people think.

It doesn't hurt to have a lot of power available unless you are using headphones that cannot handle a lot of power.
In this case you run the risk of burning out the voice coils by accident (when not on the head) but will never run into clipping.
Having a surplus in power of a factor 10 won't hurt but will never be used, but also will never have to worry about possible clipping.

Having too little power (voltage actually) won't damage any voicecoils but higher impedance headphones won't reach decent SPL levels.
Driving an HD800 or HD600 from a Sansa clip won't give a satisfactory sound simply because the output voltage clips before a decent level is reached.
IF you only like to play it softly there is no problem.
People draw the conclusion they need more power.
They DO of course as power is related to voltage (P (watt) = U²(voltage) x impedance (Ohm)) but what they really need is more voltage

Because of these facts the myth is born 'more power = better sound'.
It has some truth in it though.

Having an amp that can deliver 10W, if your headphone can only handle 0.2W, won't sound better than when playing it from an amp that can deliver 1W.
Of course you also need to include the psycholgical factor of having the 'knowledge' the amp will never reach its limits and you have 'power' in your hands.

For instance, an amp may deliver 1W into 16 Ohm but into 600 Ohm the same amp will only deliver 0.025W (assuming the current limit is not reached and output resistance is low)
Someone that THINKS he just bought a powerfull amp (it is 1W for heavens sake!) will not drive a 600 Ohm very loud.
So.. he thinks.. I need a much more powerfull amp.
He doesn't, he just needs a higher output voltage.
He could play it loud on an amp with a very low output power but with a high output voltage (and thus little current)

It works the other way around too.
An amplifier that can deliver 1W into 600 Ohm only needs to deliver 40mA (60mA pk) to achieve that power.
Lets assume it is current limited to 60mA.
When you connect a 20 Ohm headphone to that same amp it will only deliver 0.032W into it.

VERY few amps will deliver the same wattage into a wide range of impedances.
Most amps are current limited or have a limited output voltage swing or both (C'Moys for instance)

Power specs are MEANINGLESS unless they are accompanied by the headphone impedances that it must drive.
This too adds to the power confusion on the web.
Manufacturers do like to 'list' numbers and so they list the highest number.

This is just the technical part though, as many will say that doesn't account for everything that is perceived.