Quoting the same figure for all 3 impedances certainly would cause us to suspect it's wattage input, which is efficiency as per Emotiva's specs. And another search on that basis finds someone with a test report confirming that:

"The sensitivity of the Beyerdynamic DT 880 Pro headphones is 101.53 dB/V SPL by the voltage and 95.56 dB/mW SPL by the power. The sensitivity by voltage reflects the relative "loudness" of the headphones among others - the higher is the value, the louder are the headphones."

https://reference-audio-analyzer.pro/en...#gsc.tab=0

So the GR1s are claiming 10dB higher SPL if they also are measuring 1mW input.

Neither are provided with very clear specifications regarding Sensitivity - for the DT880, Beyerdynamic state 96dB sensitivity without any qualification.

Beyerdynamic qualifies it in the datasheet:

Nominal SPL ... 96 dB
(all specifications according to EN 60 268-7)

This is a clear, but only implicit specification. "EN 60 268-7" is an international standard, but I can't find this text at the moment (and payware probably).

But I'm quite sure this modern standard is the SPL at 1 kHz and 1 mW.

@dklein
Because of the weak level of the Steinberg, I am not sure, if it has a real (active electronics) headphone amp inside at all. Are you sure the headphone out is not just the Line out tapped with resistors? Could be an explanation, why your GR-1 sounds less "open" and bassier, because the volume pot has another level (40% vs. 100%) and this implicates a higher output impedance when carried out just with resistors. Just an idea ...

The GR1s are credited with Efficiency of 106 dB, also without any qualification.

Sensitivity and Efficiency are not exactly the same thing, but if perchance the two terms are being used to describe the result of the same test conditions, that would lead us to expect a higher sound level from the GR1 on the same input signal.

hehe, I know that effect with this cans too :-)

But the headphone out of the Steinberg ur-22 mkII must be pretty weak, when you run your "880 at full volume", interesting.

I don't run them more than 1/3 fullscale on my 2i2 gen2.

The bass sounds neutral with my setup, what I like. But I guess I know, what you mean.

I drive my powered monitor speakers and my headphones with a Steinberg ur-22 mkII, and just got the new Emotiva GR-1 graphene vapor-deposited membrane headphones, to replace my Beyerdynamics 880 set.  Both are 32 ohm rated, but I run the 880 at full volume off the ur-22, but have to dial back about 40% to match the volume levels when listening to the GR-1.  And the 880 seems more open, as with them there's more of the "am I hearing headphones or speakers?" sensation, though the bass is better with the Emotiva GR-1.

All in all, definitely 'a first world problem.'

Even on my digital devices, altering input thru to output volumes can still result in old-world analog "hot" or "pallid" signal.

Since these devices run on modest voltage supplies internally, the resistance only needs to be small. More professional type gear like mixers can provide higher output voltage to headphones, so typically a higher output series resistance will both provide the desirable short circuit protection, and also attenuate the output level to the headphones, to stop the listener from accidentally blowing their ears up, or damaging headphones (or vice-versa).

It might be worth mentioning that output impedance can also influence the character of headphone sound, both from the point of view of frequency response and damping.

Headphones can be designed with either low or high impedance sources in mind, but it's not often specified which design philosophy has been followed. You may see, for example, studio monitoring 'phones specified as something like: Designed for source impedance 120Ω - 250Ω

Classic studio headphones are the most likely to have been designed to work with high output impedance devices, since historically the headphone outputs from power amplifiers and mixing desks incorporated these sort of values of series resistance. This amount of resistance will interact with the reactance (inductance and capacitance) of headphones, resulting in frequency response variations, and provide no effective damping to control unwanted diaphragm movements. So this style of 'phone will be well damped mechanically and will have been designed to have the desired frequency response when driven from the appropriate source resistance. A few people may have been underwhelmed listening to highly recommended studio monitoring headphones on a modern mobile device, where very low output impedance can over-damp the drivers and deliver a sound that might be described as lacking in energy or a bit dull. Whereas driven from a more suitable device they would come alive.

Conversely, most modern headphone designs would have been developed to work with these low impedance devices, and if plugged into an old school mixing console could end up with a lumpy frequency response and poor imaging from undamped resonances and phase anomalies (assuming the 'phones are good enough to let you hear those differences).

I found ~10 Ohm for both, UMC202HD and 2i2gen2.

Not bad, I had expected around 47 Ohm that I found in a Behringer mixer in the past.

PS:
@400 Hz, 1 V, Load resistance 92.9 Ohm

Thought I was looking at gen 2 there - explains my confusion. Thanks so much for this interesting food for thought

It is good Focusrite changed the symbols, so its special function gets clearer (channel 1 and 2 are mixed and distributed to L and R of the Headphone out AND the Line out).

DIRECT MONITOR in my tested Behringer and Focusrite is just another wording for routing the analog input analogically to the headphone out and the line out at the same time.

The Behringer does not mix those channels on this path, while the Focusrite additionally mixes and splits both input channels so that L and R have the same signal ("stereo").

I have to say I'm using those Audiointerfaces just as DigitalAnalogConverter and Headphone-amp for outputting Pianoteq :-)

Cheers Qexl!