[lsc04361]

Hi. I used to think DAC will have a bigger impact on how the music sound, as its after all where the digit convert to analog signal.
But recently I have try to plug the headphone to line-out, where the analog signal hasn't been through the amplifier, and the music sound quite different than the case with an amplifier.
Are they both have more or less equivalent effect on how the music is reproduced?
 
By the way, I have always wondered how amplifier works. The signal from the line-out is of some level of voltage, and enough to drive the some low-impedance-headphone already. And the loudness of each frequency of the sound is determined by the amplitude of the analog signal. So what is it exactly, have the amplifier processed or "amplified"?
 
Thanks.

 

[MindsMirror]

  Hi. I used to think DAC will have a bigger impact on how the music sound, as its after all where the digit convert to analog signal.
But recently I have try to plug the headphone to line-out, where the analog signal hasn't been through the amplifier, and the music sound quite different than the case with an amplifier.
Are they both have more or less equivalent effect on how the music is reproduced?

While your reasoning is true that the DAC is critical to the sound, upgrading it tends to have only a small effect. This is because with the current level of technology, even cheap audio DACs are already very good.
 
An amplifier is designed to supply power, a DAC or line-out is not. Power is a combination of Voltage and Current, so while the line out may have sufficient voltage, it might not be able to properly supply enough current to power the headphone.
 
If you aren't very familiar with electronics, it might be easier to understand a physical analogy first. Think of the power steering in a car. Without power steering, the driver has to exert a lot of effort (power) to turn the steering wheel. With power steering, the driver still turns the wheel the same distance, but the hydraulic or electric motor supplies the power to turn the wheels with very little effort required from the driver.

 

[lsc04361]

Thanks for your reply.
I understand the importance of amp when powering a high impedance headphone.
But how about low impedance cans? Something can be driven with little energy. What makes a good amp to sound betterin these cases?
I used to think with low impedance cans, there much less to gain for using a good amp. But when i plug the headphone directly to lineout, the volume is enough, but it sound so different. I would like to know why is that so.
I'm guessing maybe its related to the different energy level of different frequencies. Higher frequency has more energy, so given the same current, the higher frequencies will carry more energy(is it really the case?), plus certain frequencies are better received by ears, therefore the music might sound loud enough in general, but the bass might not be as "enough" as the other frequencies, which caused the different if the perceived sound. But is it really the case?

 

[MindsMirror]

Amps are needed for both low and high impedance headphones but for different reasons. High impedance headphones need relatively high voltage and low current, while low impedance headphones need relatively low voltage and high current.
 
A line out may not supply enough voltage for a high impedance headphone, so it needs an amp with high gain to get enough volume.
 
For a low impedance headphone, the line out might supply enough voltage, but can't deliver the necessary current without creating distortion. One reason for this is the high output impedance of a line out or a bad amp. The output impedance interacts with the headphone's impedance and will alter the frequency response. If the headphone's impedance is low, the output impedance is much more significant in comparison. A 32 Ohm output impedance is very significant to a 32 Ohm headphone, but compared to a 600 Ohm headphone is it not very significant at all so it will have little effect.

 

[obobskivich]

Amps are needed for both low and high impedance headphones but for different reasons. High impedance headphones need relatively high voltage and low current, while low impedance headphones need relatively low voltage and high current.

A line out may not supply enough voltage for a high impedance headphone, so it needs an amp with high gain to get enough volume.

For a low impedance headphone, the line out might supply enough voltage, but can't deliver the necessary current without creating distortion. One reason for this is the high output impedance of a line out or a bad amp. The output impedance interacts with the headphone's impedance and will alter the frequency response. If the headphone's impedance is low, the output impedance is much more significant in comparison. A 32 Ohm output impedance is very significant to a 32 Ohm headphone, but compared to a 600 Ohm headphone is it not very significant at all so it will have little effect.

Agreed with all your responses to the end of the last paragraph. The output impedance will only interact with a reactive load, and there is no absolute "true" frequency response (e.g. a reactive load is just that: reactive; the frequency response will always be varied with respect to source impedance). A lot of low impedance headphones (especially planar magnetic designs) are usually fairly non-reactive, so their interaction with output impedance is usually very minimal. A big exception here are multi-driver IEMs that usually are not only reactive but have multiple peaks in their impedance (due to the multi-driver design) which can experience more dramatic frequency response variations with respect to source impedance (typical dynamic headphones usually experience an impedance shift around driver resonance, which is usually in the mid-bass).

The IEC standard actually calls for a relatively high output impedance (120 ohms) with the intention of providing consistent output and distortion performance into a variety of loads, and an amplifier that properly follows this guideline will indeed behave fairly similarly into a wide variety of loads, however with some reactive loads there will be an impact on frequency response relative to a lower Zout device (which leads to "what's better" -> that's up to the listener). Current-source amplifiers take this principle to a hyperbolic extreme.

 

[lsc04361]

Amps are needed for both low and high impedance headphones but for different reasons. High impedance headphones need relatively high voltage and low current, while low impedance headphones need relatively low voltage and high current.

A line out may not supply enough voltage for a high impedance headphone, so it needs an amp with high gain to get enough volume.

For a low impedance headphone, the line out might supply enough voltage, but can't deliver the necessary current without creating distortion. One reason for this is the high output impedance of a line out or a bad amp. The output impedance interacts with the headphone's impedance and will alter the frequency response. If the headphone's impedance is low, the output impedance is much more significant in comparison. A 32 Ohm output impedance is very significant to a 32 Ohm headphone, but compared to a 600 Ohm headphone is it not very significant at all so it will have little effect.

Excuse me, but i still got some questions.

If the amplifier can drive the headphone to a volume of even a deafening level, given that the output impedance of the amplifier, does it mean that amplifier is good enough for that particular headphone?

I have read many articles claiming that, even in such case, a better amplifier can make the sound better. One article stated that it has something to do with the clipping of the amplifier, that even the clippingis not quite audible, it may alter the overall presentation odf the sound. But I'm wondering if that is another myth within tge audiophile, like the case with better power cord or usb cable.

Thanks for all of you guys' reply so far by the way.

 

[obobskivich]

Excuse me, but i still got some questions.

If the amplifier can drive the headphone to a volume of even a deafening level, given that the output impedance of the amplifier, does it mean that amplifier is good enough for that particular headphone?

I have read many articles claiming that, even in such case, a better amplifier can make the sound better. One article stated that it has something to do with the clipping of the amplifier, that even the clippingis not quite audible, it may alter the overall presentation odf the sound. But I'm wondering if that is another myth within tge audiophile, like the case with better power cord or usb cable.

Thanks for all of you guys' reply so far by the way.

Basic logic should prevail here, but we're well into the land of audiophilia nervosa - if it isn't audible, it isn't audible, which means you can't hear it, which means you can't hear it, which means it doesn't matter, because it isn't audible, and you therefore can't hear it. :eek:

There's a lot of historic marketing along the lines of "just because XYZ product [usually not a dedicated headphone amplifier] can drive your headphones with low distortion, no audible clipping, and more than enough power for their needs - ITS WRONG AND YOU MUST BUY OUR GOBBLESNORT XXL DEDICATED HEADPHONE AMPLIFIER (because that's what we sell and we gotta eat too)"

Yes that's a hyperbolic exaggeration, but it isn't *that* far from the truth in some cases (and I will add that a lot of modern makers do not push that line - usually they're selling something that has appeal because it fits into a form factor that's more conducive to portable or desktop use, or has connectivity features that are more relevant to modern usage, etc). That all having been said, amplifiers CAN (and DO) make a difference for the sound (for headphones and speakers), but the discussion should really be more along the lines of "how does this specific amplifier pair with this specific headphone?" And don't expect a singular, linear, unified listicle kind of answer that highlights the "best to worst" configurations available. There's lots of good devices out there which can drive a huge range of headphones very well. If it can drive the headphone to a good volume level with sufficient reserve for dynamic range, without audible clipping or distortion, and has good channel tracking and acceptable noise floor (and "acceptable" really has to be to your own tastes - some people care more/less about background noise), then its passed the burden of compatible + suitable. At that point, it comes down to personal preference if you like how the setup sounds vs another amplifier in the same role. The differences are not going to be earth-shattering, but can be there, especially if you're dealing with a more reactive load and changing output impedance (and again I'd throw that "rule of 1/8" completely out the window).