I would be very much interested in an informed discussion as to the technical merit of standalone headphone amplifiers for purposes other than providing a needed boost in volume or gain or headroom (pun intended, see Headroom at headphone.com ).

I do not have the technical expertise to contribute to a discussion on the matter that would meet the common posting standards of hydrogen audio. I can only state my hypothesis that headphone amplifiers are of little or no benefit unless a source such as a weak portable or soundcard truly cannot deliver the power needed for the volume desired without clipping or audible distortion, which I think is probably a pretty rare occurrence. Otherwise, won't the amplifier pass on the frequency response or noise-floor deficiencies of the source, and add another layer of signal processing with some at least minimal level of distortion to boot? To put it bluntly, to the best of my minimal understanding, expensive headphone amplifiers seem to be a preposterous rip-off.

I've tried to ask a reasonable question; it may be I do not even have the expertise to form the question properly. And I'd be fascinated and not offended at all to be proven wrong. FWIW, I am coming to hydrogen to ask this in the hope that more light than heat will be shed on the subject.

Thanks!!!!

[Edits to clean up my writing.]

I was on their website and read through their amp section a lot. not sure if i should get the lite headphone amp or not.


but the sound processor inrests me which makes headphones sound like speakers not like left and right. I think a headphone amp will make the sound a little better. francly I believe them when they say a headphone amp is for headphones and improves sound, but I dont know until I get my lite, which is still a while away, no money!


if anyone wants to give me some money to test a headphone amp please pm memeeeeeeeeee

I'm curious about this too. Theoretically, a better amp should give you better sound, as long as it's able to reproduce the sound better (less compression, less clipping). But since we're plugging this after the headphone jack, we're feeding this expensive amp with the output of the other, supposedly not-so-good amp. In this case, isn't the damage already done?

Unless, adding the external amp would allow you to run the internal amp in the portable at a lower level, and maybe the portable's amp has better fidelity when it's outputting a lower volume than otherwise. This could be the case, if the problem is the power supply in the internal amp.

But, i think this is farfetched.

This page, at headphone.com
http://www.headphone.com/layout.php?topicID=2&subTopicID=15
also mentions power supply fluctuations. They give another possible reason to use an external amp: to isolate the internal amp from the "difficult load" of the headphones.

g

i think that this kind of external amp has a line-level input so you can use the standard preamplified output instead of the headphone jack, IIRC most of them are also equipped with a build-in volume control so direct connect to the output of a cd player should be possible.
Maybe some regual amplifiers have a very poor quality output stage driving the headphone jack (a little technics form a friend of mine made very strong noise while trying to turn up the volume using headphone....) so an external amp can help a lot in this cases.
There're also some "exotic" headphone with a lower sensibility (electrostatics form Stax and the top of the line from AKG IIRC) and probabily with these headphone an external amp is mandatory (very expansive solution btw )

I think it's pretty much what Shark described. I don't really believe you'd necessarily need a dedicated amplifier, just something with a good headphone jack. I have a JMT built CHA-47 headphone amp which I don't use, this is my "headphone amp" for HD580s. And as Shark said, you're supposed to connect amps via a line-out (typically directly from either the CD player lineout or a seperate DAC), not with a headphone output...that wouldn't make sense.

There are two issues solved by headphones amps : in the audiophile market, many devices don't have any headphone output. Actually most amplifiers don't. For their owners, a dedicated headphone amp is the only way to listen to vinyls. Normal CD players often have an headphone output, but some audiophile ones don't, especially the trasport + DAC combinations.
The other issue is the output impedance, that audibly affects the frequency response, because it interfereres with the impedance of the headphones. All I know is that power amplifiers often have 330 Ohm headphone outputs (330 Ohm resistors in serial with the speaker output). If an headphone amp has a lower impedance, it will provide a different frequency response.

my new AKG headphones sound ******* amazing with my mpc 7 quality songs

hd -> ide cabel -> motherbaord -> northbridge ->mobo ->ram -> northbridge -> CPU -> northbridge (if i am not mistaken in thsi order) ->audigy 2 zs ->gold cable -> denon F10 amp -> headphone out -> cable -> headphone

wahhhhhhhhhhhhhhh

Yes and no. A whole lot of expensive hifi kit is a rip-off but you need to differentiate between "good" kit and "expensive" kit. There is a very loose connection between price and quality with hifi kit, especially with real top-end stuff.

On the other hand, headphones are quite hard loads for an amp to drive which means that you need a good amp to drive them properly. Basically you need an amp which can drive a headphone type load while remaining linear and not clipping (at all).

Basically, an amplifier tries to feed a voltage waveform to a load (speaker or phones) which causes a current to flow. When the current gets to high for the amp to supply, the voltage drops and the sound is distorted. A good amplifier will not allow this to happen, because it is designed to be able to source enough current so it can provide a clean waveform right up to maximum volume.

Another source of distortion is introduced when the amplifier output voltage exceeds the supply voltage (clipping). This is purely a matter of trying to supply more volume than is available. A good amp should never be driven into clipping without severe provocation (enough to deafen you or kill your headphones).

Basically, before you strike out too strongly against headphone amps, understand how they work, what they do and what benefits they have for your sound. Listen to a few and see if you hear a difference. And it needn't be very expensive - you will be surprised at how cheap it could be to build or buy an amp which could greatly improve your sound.

Good headphone amps are not a rip-off. Expensive headphone amps might be.


If you are using a computer as a source this is probably best done in the digital domain. It has been discussed plenty of times around here before - no need to shell out hard earned cash for something you can get for free. I have a personal belief that analog signal processing is evil, but on the other hand the circuit for this kind of cross-feed would be very simple.


No, not really. The low quality amp will deteriorate the sound to some extent, but most amps perform much better into a multi kiloohm load (like another amp) than a few ohms or hundreds of ohms load, like a set of headphones.

Got it, thanks!

Now the $150 question is: how much? Headphone.com amps go from about $150 to about $3,000. Even $150 feels a little like a rip-off to me, since most portable CD units cost less than that.

g

umm, none. fact is, a headphone amp is fairly large and when you're walking around there's so much noise and such that sound quality really ain't that important. it's not worth it, believe me.

Do people use headphone amps with PC systems + headphones as well or is there no point?

err headphone amps are not ALL large

http://www.fixup.net/products/inlineamp/index.htm

I have the super mini which is a little bigger.. still about as big as a box of matches... nice sound over my nomad jukebox3's standard output..

Most would be using headphone amps at home though without any concerns of size or portabilty.. I think everyone on this forum knows a lot about headphones though as they are the output device of choice for testing codecs artefacts and ABX-ing..

I love all my types of headphones, i do believe an amp is worthwhile.. especially if you have nice headphones and a crappy source amp driving them.. I can't believe the difference on my Sennheiser HD600s from my hifi amp and a smaller more portable cd player/radio including attached speakers... admitedly not a great source anyways but sounds quite nice for a bit of room filling sound for my parents over speakers but driving my headphones there was pretty much nothing to enjoy.. no volume... no clarity at all just muddy sounding...

Honestly, I just don't believe it. Yes, I've had problems with headphone outs on cheap equipment, the biggest problems being hiss and problems with channel balance (made very obvious at low volumes), and an amp just won't fix that. But for the price of an average headphone amp, you can get a piece of gear that doesn't have these flaws and has a fine headphone jack.

Full disclosure, I have a nice headphone amp, and use it all the time, because it gives me great confidence, I've put the thing through the mill trying to find something wrong with it (as I tend to do!), there is no hiss, the sound never disorts, the channel balance is perfect, and the crossfeed (3 settings) is very nice and tastefully done too. (It's a Corda HA-1). But I've also done a lot of comparing, and I do firmly believe that the headphone jack on a good Sony component CD player or well-selected low-priced receiver (cost: $100 - $200) will max out the sound quality of a pair of Senn HD580s (which I own) with room to spare, and that any claim to the contrary is false. This isn't the result of blind A/B testing (and neither are any of the other assertions in this thread, and it's very hard to conceive of a blind A/B setup that will not be criticized by "believers" for lengthening the circuit path!), but I am obsessive about such things and I've compared until I was about to collapse, and that's the most honest conclusion I could reach.

As some support for what I'm saying, I do note that Sennheiser's own HD580 manual (I have it right here!) indicates that Sennhesier headphones are manufactured to match the industry standard equipment impedences and that any "any problems with the connection would be an exception," (it's translated roughly from German), hardly an endorsement of headphone amps for one of the most obsessively amped headphones out there. (The HD580s are claimed by the headphone amp folks to be a fairly tough load by headphone standards.) Further, the manual praises the headphone jack on modern equipment, referring to new models equiped with a "special output for headphones," (lay terms -- a headphone jack!!!) and states that "there's no need to worry about amplifiers." Again, hardly an endorsement of headphone amps from one of Sennheiser's most commonly amped headphones. In sum, a close reading of the manual indicates strongly that the HD580s are designed to be driven by the standard headphone jack found on component audio gear, and that you need not concern yourself with anything more... this combined with my listening experiences makes me believe that the vast majory of use of headphone amps is purely superfluous and unnecessary -- money not well spent.

[Edit: grammar.]

There is quite a bit of difference between the standard output of a PCDP and the line-out run through a good headphone amplifier. For the experement, I recorded white noise (generated by CEP) with a LD-condensor mic pressed up against my HD 600 being driven by either my Panasonic SL-CT780 PCDP or my HeadRoom Max. I then used CEP's FFT and Mathematica to generate the statistics of the data points from 20Hz to 20kHz:

Variance -> 1.35439 dB
StandardDeviation -> 1.16378 dB
SampleRange -> 16.1119 dB
MeanDeviation -> 0.614532 dB
MedianDeviation -> 0.426418 dB
QuartileDeviation -> 0.426596 dB

Here is the plot of the difference, where the vertical axis is dBFS and the horizontal axis is log base 2 hertz.

I do. I have tended to use difficult to drive headphones with my computer, like Beyerdynamic DT770-250s which were 250-ohm headphones and very picky about what juice supplied them. Now I use Grado SR225s which are current-hungry phones and my amp provides far more current than a soundcard can which helps drive them more cleanly. I also like the coloration my amp gives to the sound overall and how I can easily try various opamps in it for a change in sound. My amp costed less than $100 to build and does its job more than well enough. I do want to build another one eventually, but mainly to have something that is built with better quality as my current amp is more of an experiment that just happens to work than a finished product.

Thanks, it's nice to know there is a measurable difference. I did buy a mid-priced panasonic portable, but unlike yours with no line out, and returned it because the headphone output had too much hiss. I've had best luck with Sony portables, both with the line outs and the headphone jacks. My I-River IMP350 (which blows the Sonys away for features) seems to have really good sound too, but there is some minimal level of audible hiss. I do usually use a headphone amp with my PDCPs if I'm in a situation where I can listen closely, though I'm not always convinced it's making that much of a difference. So it is nice to know you found some measureable differences.

Hello

I use a Grado SR80 headphone.

Before I bought it, I listened to serval headphones:

Grado: SR60, SR80, SR225, RS1
Sennheiser: HD560, HD670, HD580, HD590, HD600
Some AKG

For my listening-Tests I had the choice between the headphone-output of the CD-Player an the Headphone Amp(http://www.gradolabs.com/product_pages/ra1_amp.htm)

ALL headphones sounded better on the Grado headphone amp than on the headphone-output of the used High-End CD-Player.

The signal was clearer, wider, voices more natural etc.

At home I use several Amplifiers. One of them connects the headphone directly to the power amp. With this amp, the Grado sounds nicer than with the other ones. (All of them were quite expensive when they were new)

For me it is clear: If you want the best sound with your headphone, use a headphone amp.

I only use it in the night, about 1 h per week, so I did not buy one, but I would if I used it more often.

cu
Etienne

I decided to do another test, in which I compared the HeadRoom Max to a mid/high-end USB soundcard (Edirol UA-5). Here, the results where much closer than I expected. The numbers are:

Variance -> 0.0177585 dB
StandardDeviation -> 0.133261 dB
SampleRange -> 6.49229 dB
MeanDeviation -> 0.0997344 dB
MedianDeviation -> 0.100906 dB
QuartileDeviation -> 0.0975523 dB

Frankly, I was quite shocked. I always thought the Edirol's headphone output was horrible sounding, but it seems placebo was having the best of me. Here is the graph:



Of course, neither of my tests would show how noisy the headphone outputs are. While the Max is dead silent even at full volume, I can't say the same about the other sources. For a proper test, I would also have to analyize a sweep (instead of just white noise) and probably a couple impulse response (or square-wave, for that manner). I suspect, these would show even more of a difference.

That's just awesome information you've provided about the headphone amp, PDCP and soundcard outputs. I've never seen anyone tackle the question head-on before. I just don't have the means or expertise. Thank you.

thats decided then.

i will buy a headroom lite amp.

i cant people are moaning it cost $150. thats cheap....... even though i dont have the moeny to get one for 3 4 months.

Yes, get me this kind of money and I'll buy Super Mini and save a lot of money.

Several years ago I bought a Naim Nait 3 integrated amp. It didn't have a headphone jack, so I needed a headphone amp to listen with headphones.

After using and listening to the amp I felt like I'd been ripped off and couldn't tell the difference between the headphone amp and the headphone output of a CD player (purchased a couple of months after the headphone amp) and the headphone amp. I was quite disappointed.

The headphone amp sat in my stereo cabinet for years without being used. Two years ago, I bought a Linn Classik and now with a first rate source I decided to try out the headphone amp again. Holy cow, was it ever amazing! The sound quality is great and now I feel like I got a bargain when I bought the amp.

If you have a lousy source, then yes you won't be able to appreciate how good the headphone amps on www.headphone.com are, but if you plan on using a good source, they're great.