#### Francis Vaughan

##### Addicted to Fun and Learning
Forum Donor
There is potentially a lot to worry about driving such low sensitivity and low efficiency headphones.
One needs to be clear about terminology.
Gain is generally voltage gain. Volts on the input * gain = volts on the output. This makes some important assumptions, but in the systems we use, this is a good definition. We don't care about input impedance, and we consider power amplifiers as voltage sources. So it is OK. (We should pedantically, use power gain, but we don't define a known input impedance, so we can't. Expressed in dB we just define the gain as 20*log(voltage gain) instead of 10*log(power gain) and it all works out.)

A perfect voltage source has of course the ability to source infinite current, so when it can't, we have issues. We can probably break the problems into a few parts.

All amplifiers are usefuly modelled with their Thévenin equivalent, which places a notional resistor in series with the perfect voltage source output. So long as the Thévenin resistance is small relative to the headphone impedance it isn't a big issue. This resistance is for conventional amplifiers pretty much the resistance of the output devices + power supply impedance, all divided by the feedback factor. Poor output impedance can lead to frequency response issues. The output impedance and headphone impedance form a potential divider. Your useful voltage is the voltage seen out of this divider. Beware headphone amplifiers that put a real resistor on the output. They exist.

The linearity of output stages can be very sensitive to the load impedance. Transistors are not exactly linear devices at any time, and as the forward current increases the overall linearity of the output stage can suddenly start to become significantly non-linear. So much so that the performance of the amplifier starts to suffer. This is independent of the power supply capability. Feedback can only reduce the distortion by a fixed ratio. You can see this in Amir's stress measurements of any amplifier into low impedance loads. Such behaviour can mean much worse than expected distortion.

The power supply reserve can be depleted. Once the power rails start to sag everything can begin to go wrong. You can no longer be sure the amplifier is even operating correctly, and all manner of internals might have a transient failure. Distortion might rise to extraordinary levels until the rails recover.

A lot of headphone amplifiers will get into trouble driving a 40Ω load. Some will curl up and die, some will misbehave, and some will just sound bad. It isn't trivial to guess which ones will behave well. Proper performance measurements are a very useful guide. Marketing isn't.

#### Robbo99999

##### Major Contributor
Forum Donor
There is potentially a lot to worry about driving such low sensitivity and low efficiency headphones.
One needs to be clear about terminology.
Gain is generally voltage gain. Volts on the input * gain = volts on the output. This makes some important assumptions, but in the systems we use, this is a good definition. We don't care about input impedance, and we consider power amplifiers as voltage sources. So it is OK. (We should pedantically, use power gain, but we don't define a known input impedance, so we can't. Expressed in dB we just define the gain as 20*log(voltage gain) instead of 10*log(power gain) and it all works out.)

A perfect voltage source has of course the ability to source infinite current, so when it can't, we have issues. We can probably break the problems into a few parts.

All amplifiers are usefuly modelled with their Thévenin equivalent, which places a notional resistor in series with the perfect voltage source output. So long as the Thévenin resistance is small relative to the headphone impedance it isn't a big issue. This resistance is for conventional amplifiers pretty much the resistance of the output devices + power supply impedance, all divided by the feedback factor. Poor output impedance can lead to frequency response issues. The output impedance and headphone impedance form a potential divider. Your useful voltage is the voltage seen out of this divider. Beware headphone amplifiers that put a real resistor on the output. They exist.

The linearity of output stages can be very sensitive to the load impedance. Transistors are not exactly linear devices at any time, and as the forward current increases the overall linearity of the output stage can suddenly start to become significantly non-linear. So much so that the performance of the amplifier starts to suffer. This is independent of the power supply capability. Feedback can only reduce the distortion by a fixed ratio. You can see this in Amir's stress measurements of any amplifier into low impedance loads. Such behaviour can mean much worse than expected distortion.

The power supply reserve can be depleted. Once the power rails start to sag everything can begin to go wrong. You can no longer be sure the amplifier is even operating correctly, and all manner of internals might have a transient failure. Distortion might rise to extraordinary levels until the rails recover.

A lot of headphone amplifiers will get into trouble driving a 40Ω load. Some will curl up and die, some will misbehave, and some will just sound bad. It isn't trivial to guess which ones will behave well. Proper performance measurements are a very useful guide. Marketing isn't.

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#### PeteL

##### Major Contributor
This is how I look at it.

"gain" is just a "spec" telling you the ratio between input and output. What really happens when observing the "load" is P=V * I

There is no such thing as having enough "gain" (V) on the load but not enough power, or vice versa.

The issue is when there is current limiting going on, and therefore the voltage (V) on the load will be limited by the current (I) capability.

In that case, I imagine, what happens is peak current, high energy transients (aka high frequency component) will not be limited as will (RMS) high power , low energy transients (aka low frequency component).

You are not wrong, Ohm's law is always respected, and yes the effective gain will drop if current drop because of a lack of power, the 3 are always linked, but the Key here is that the voltage drop will be content dependent and instantaneous and not necessarily translate in a perceived level drop. basically, The gain, or output voltage, is fixed by the volume pot and will only drop when the power supply can't supply the current, that can be an instant peak, or Bass notes because in the mix they need more energy to be heard as loud as the rest. In short, an amplifier can play loud enough and still be lacking power.

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#### max1236

##### Member
So what is the wattage requirement for he6se? I know some people say you have peaks up to 115db so you need 6 watts into 50 ohms but I always thought that was kind of ridiculous. Wouldn't a peak that loud be way to much?

#### abdo123

##### Major Contributor
Forum Donor
So what is the wattage requirement for he6se? I know some people say you have peaks up to 115db so you need 6 watts into 50 ohms but I always thought that was kind of ridiculous. Wouldn't a peak that loud be way to much?

not really, sub-bass at 110 dB is very tolerable to me.

#### Tks

##### Major Contributor
not really, sub-bass at 110 dB is very tolerable to me.
Except he is generally speaking. Sub bass tolerance isnt really ever a talking point for pain thresholds. Its everything else that is.

#### PeteL

##### Major Contributor
Except he is generally speaking. Sub bass tolerance isnt really ever a talking point for pain thresholds. Its everything else that is.
But he was talking about wattage requirement, that’s exactly the metrics that are relevant, not general treshold of pain talks.

OP

#### amirm

Staff Member
CFO (Chief Fun Officer)
So what is the wattage requirement for he6se? I know some people say you have peaks up to 115db so you need 6 watts into 50 ohms but I always thought that was kind of ridiculous. Wouldn't a peak that loud be way to much?
As I mentioned, I listened using Topping A90 in medium gain (balanced) and that was enough. Here is its measurements:

Medium gain produces a bit more than 1 watt at 50 Ohm. So close enough. Max power in high gain is 4.8 watts which is more than plenty so that 6 watt number doesn't make much sense. I measured 114 dB using the A90 and it was below its max power.

#### Francis Vaughan

##### Addicted to Fun and Learning
Forum Donor
If we take Amir's good panther ratings of headphone amps I'm thinking we can generally accept they will drive almost any headphone with a 2V DAC unless it's a portable headphone amp, is that a reasonable "black box" assumption? I think I'm right in thinking that when Amir comments on his inefficient Ether CX headphone and the amps ability to drive that one, that we've got the bases covered?

The output ability of the DAC is mostly immaterial. 2V is good in that you are assured of the signal staying well away from the noise. Power amplifiers usually have some gain, indeed designing a unity gain power amplifier can be a bit of a problem, so there is usually gain to spare to make up for a DAC with lower maximum output.

But overall, yes, the above is a good start. If Amir is cheerfully rattling his teeth with the Ether CX, you are not going to have any problems.

#### GaryH

##### Active Member
They are only better on a list generated by an algorithm based on measurements on a specific rig and not ranked to tilt (tonal character) either.
It's just a list. Very similar to a SINAD ranking.

They are not similar at all. There is no solid scientific evidence electronics' SINAD has a strong continuous correlation with preference. Its only use related to audibility is to show if a DAC/amp is either broken or adequate for its purpose. The Harman algorithm in contrast has an 86% correlation with listener preference in scientific blind studies and it does take tonal tilt into account. In fact this has the majority weighting in the algorithm. The tonal tilt of the Hifiman Sundara (-0.12) and 400i 2020 (-0.1) are equally close or closer to neutral (slope = 0) than the 6se (0.12). And the tilt of the 4xx (0.19) is only 0.07 from the 6se both being slightly bright. The specific rig used for the measurements these figures are calculated from is an industry standard set-up that is the same within margin of error as that which produced the data Harman's algorithm was developed from.

#### Anmol

##### Member
Forum Donor
\$1800 and the cable crackles? Next....
Double the money and get abyss. Cable doesnt crack but sound from headphone cracks.

#### roskodan

##### Member
Cracking would be Focal headphones' sound, still better than Abyss tho.

#### mkawa

##### Addicted to Fun and Learning
it's been said that adorama has these on special every frequently. should i subscribe to their newsletter to not miss the next sale? these are the reason i have an sp400..

#### bigjacko

##### Senior Member
Isn't it on back order until August? How did it come out a few weeks ago? How do you sign up for the deal on Adorama?

#### aldarrin

##### Member
Isn't it on back order until August? How did it come out a few weeks ago? How do you sign up for the deal on Adorama?

The Adorama deal was for a slightly different model (HE6se V2). Same drivers but different suspension. They sold all of them so they aren't available. When they were in stock they'd sell for \$1799 or \$650 - \$750 with a special link (that everyone seemed to have). Hopefully they become available at \$650 as they seem very appealing at that price.

#### AVKS

##### Member
The Adorama deal was for a slightly different model (HE6se V2). Same drivers but different suspension. They sold all of them so they aren't available. When they were in stock they'd sell for \$1799 or \$650 - \$750 with a special link (that everyone seemed to have). Hopefully they become available at \$650 as they seem very appealing at that price.

I have the V2s and while they are a challenge to drive - I typically listen at around 11:00, highest gain, balanced output on my THX-789 - they sound just so natural and effortless. With that said my source is an LG V30/G8 Quad DAC so I wonder just how much juice the 789 is putting out based on the input level of the LGs.

#### Aperiodic

##### Active Member
Double the money and get abyss. Cable doesnt crack but sound from headphone cracks.
This site is performing a public sevice by exposing how much overpriced equipment is actually under-engineered garbage. It's not that it's 'not enough better to justify the extra cost'- a lot of it is actually worse than much less costly gear.

I will say however that I would not base a buying decision on how a headphone sounds at an SPL of 114dB- a level that will literally deafen you in short order..

#### Anmol

##### Member
Forum Donor
This site is performing a public sevice by exposing how much overpriced equipment is actually under-engineered garbage. It's not that it's 'not enough better to justify the extra cost'- a lot of it is actually worse than much less costly gear.

I will say however that I would not base a buying decision on how a headphone sounds at an SPL of 114dB- a level that will literally deafen you in short order..

#### Jave

##### Active Member
I wonder how this compared to the much cheaper HE5se

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