[JaZZ]

This thread is the result from a previous one to the same subject.

I would be glad to see only interested people reply here (hoping there won't be just two or three), whereas hooligans are asked to keep out...

It's kind of common sense that you have to use a dedicated amp to drive headphones. The first headphone amp is even part of the initiation ceremony. On the other hand, practicing and recommending the direct path without an additional amp, with just an attenuator between the source and the headphone, is a risky undertaking: the subject is mildly smiled at or called worthless nonsense; and it's just ignored by majority the old bulls.

In fact the direct path is a highly interesting issue and worth experiencing once in a lifetime for all audio enthusiasts. Why?

We all agree (I guess) that every electronics component alters/degrades the signal (i.e. the sound) it processes more or less. Take speaker amps for an example. We are used to distinguish between good sounding and bad sounding amps. There seems to be a vague dependency between expense/price and sound quality. But in fact we have no real basis for our judgement - we just don't know how a speaker should sound if the source signal has remained unaltered on its way from the CD player's line-out stage to the speaker input. We can't but accept that the best/natural sounding variant we tried is the best/natural sounding variant seen as a function of synergy between the concerned components and the own individual expectation on how good sound has to be. You may say you're not interested on how a single component sounds as long as it's a perfect match with the rest of the setup... That's indeed a possible standpoint. But consider how much money you may have invested in a speaker amp, without knowing how it alters the sound, possibly in a euphonic way... Couldn't there be ways to achieve the same sound for much less money, e.g. by just switching some sort of electronic sound enhancer into the signal path? If you still don't care, you don't have to. Maybe you have a lot of money to spend, and a well-renowned monster amp additionally serves the personal prestige...

There's just no possibility to judge the sound of a speaker amp in absolute terms. But there is one with headphone amps. You can use your source to drive your headphones alternatively! I would by all means recommend to use high-impedance headphones for such experiments: the line-out amp isn't designed to drive low-impedance loads, and there may be a certain risk to shorten its life-span with permanent low-impedance operation which causes an unusually high current flow. But no doubt: most sources are capable of driving headphones to decent levels - at least as long as their output impedance is low enough (below ~100 ohm), which at the same time guarantees that the sound won't be too much affected by the headphone's impedance curve. Use a 500 ohm potentiometer as attenuator, and you have all you need for your first step into the direct-path experience! Yes, what you hear is most likely the real sound of your CD player or your DAC, (possibly) with just very slight (and negligible) impedance-induced balance/frequency modifications. By switching your amp into the signal path, you can effectively hear its sonic signature, and not just its synergetic interaction with your source and your headphone - although it's still filtered through the concerned component's sound, but... you know what I mean?

And that's actually the main merit of the direct path: to show the actual behavior of headphone amps and - maybe to the regret of some people - their demystification and demythification!

Are the best sounding ones also the most accurate ones? I really doubt it: the sound from the direct path is unspectacular in comparison. The most accurate amp would have to sound unspectacular as well. The reason (no completeness and absoluteness of validity intended): preserved dynamic means less direct appeal. All amps I tested make the sound more rounded and warm. Maybe you know the effect from dynamic compression? The music sounds more colorful and intensive, the gaps between the notes are filled with an appealing adhesive (I guess there's also dynamic distortion included; no wonder in view of the supposed compression!), resulting in an increased coherency and even «musicality». The downside is composed of: reduced dynamic, slower transients, smeared detail, lower resolution, reduced transparency and clarity, loss of sonic and spatial focus.

I wish I could state that it's nevertheless worth to go the direct-path route. Though few people are enthusiastic about it (taoster and Czilla9000 come to mind), the limitations of today's technics seem to put it into perspective. To my ears the sound provided by an amp has more charm, is more colorful and even more «lifelike» than the direct-path sound - which in turn has a very slight technical aftertaste, at least with the digital equipment I can afford. This is not the case with an analog source, BTW, but the reason is too clear: you have a warming mechanical sound transducing process as well as an additional amplification stage there. The deduction therefrom? A digital source can benefit from some euphonic coloration from additional (and actually superfluous) amplification stages - be it due to its digital and thus data-reduced and artifact-implying nature or due to its more accurate signal path or whatsoever. So is the whole direct-path debate superfluous? I don't think so, at least not if you are interested in a look (listen) behind the (amplifier) façades.

JaZZ

 

[MacDEF]

As a moderator, I'm not sure why you purposely created a new thread on this topic, knowing that there are already three or four existing threads to which this could have been posted. Please don't do that in the future. It's much more helpful to the rest of the membership to keep the discussion in one place.

For those new to the topic, here are some previous discussions:

http://www4.head-fi.org/forums/showt...threadid=35854

http://www4.head-fi.org/forums/showt...threadid=31531

http://www4.head-fi.org/forums/showt...threadid=32785



To comment on this issue, your statements in the previous post are making two HUGE assumptions: (1) that all amps "color" the sound to a significant degree; and (2) that the line-out jack, when driving headphones, is presenting you with the "most accurate" portrayal of the source signal. Both assumptions are shaky at best.

First, many amps are designed specifically to reproduce the source signal as accurately as possible when driving the complex loads provided by headphones. There are surely imperfections, varying depending on the amp, but you can't make blanket statements that imply that amps are "coloring" the sound.

Second, and more importantly, the assumption that the line-out jack is able to provide you with a "less colored" sound when driving the complex loads provided by headphones is highly questionable. A line-level output is designed to provide the "pure" audio signal at a consistent line-level output. It simply isn't designed to drive speakers (which is what headphones are). It doesn't provide the voltage necessary to drive high impedance cans, nor the current to drive low impedance cans. Not to mention other factors (which KurtW pointed out in another thread) such as slew rate, output impedance, or damping. So there's no guarantee that the signal you hear when listening to your line-out jack via headphones is any less "degraded" than the signal being processed by a "colored" amp; in fact the opposite is just as likely to be true, if not more so, when using an amp that has been specifically designed to accurately reproduce the signal when driving headphones.


Quote:

To my ears the sound provided by an amp has more charm, is more colorful and even more «lifelike» than the direct-path sound

This is probably because the amp is actually reproducing the signal well, whereas the "direct-path sound" is hampered by your line-out jack's inability to drive your headphones well.

 

[JaZZ]

Quote:

Originally posted by MacDEF As a moderator, I'm not sure why you purposely created a new thread on this topic, knowing that there are already three or four existing threads to which this could have been posted. Please don't do that in the future. It's much more helpful to the rest of the membership to keep the discussion in one place.

[edited] Sorry, my first comment before editing was based on an obvious misunderstanding: I thought to have read you wanted to melt two threads together... The explanation for the new thread: Two of the threads you mentioned are very old, and some of my own thoughts in them need some refreshment due to the recent situation without appearing as a partly repetition which would seriously devaluate the content. The newest thread has been spoiled by impertinent and taunting posts, and the title doesn't really match the subject.

Nevertheless, your procedure is unusual compared to the numberless headphone-, amp- and source-related threads with the very same subject, the very same type and the same question - sometimes provoking according reaction in the form of links from members, but never from moderators in the shape on hand. Is this subject - direct path - the great exception, or is there any fear of scaring the sponsors away?

Quote:

To comment on this issue, your statements in the previous post are making two HUGE assumptions: (1) that all amps "color" the sound to a significant degree; and (2) that the line-out jack, when driving headphones, is presenting you with the "most accurate" portrayal of the source signal. Both assumptions are shaky at best.

I renounce to quote the rest of your reply...

You can find my test configuration which has lead my to my conclusion in this thread, among others. The assumptions are not shaky at all. Have you ever heard the direct path? Have you systematically compared it to some amps? Choose a source from which you know it has low output impedance. Listen through an amp, plug and unplug some (preferrably high-impdance) headphone to the source parallel to the amp (with a splicer/adapter) and try to verify if there's a considerable change caused by the «complex load» (represented by the headphone). There was barely any in my case. This proofs that the direct path represents more or less the original sound. The theoretical objections regarding voltage supply and impedance matching are also covered by the mentioned test configuration, so the conclusion is absolutely justified.

Furthermore: remember the vast sonic differences among headphone amps! Can any of them really be «neutral» and free of any coloration? And if so, which one is it?

BTW: As you know, I prefer to use an amp myself - no reason to fear any heresy.

 

[MacDEF]

Quote:

Originally posted by JaZZ Nevertheless, your procedure is unusual compared to the numberless headphone-, amp- and source-related threads with the very same subject, the very same type and the same question - sometimes provoking according reaction in the form of links from members, but never from moderators in the shape on hand. Is this subject - direct path - the great exception, or is there any fear of scaring the sponsors away?

Sponsors? The difference is that most "duplicate topic" threads are started by different people who either don't realize another thread exists, or who don't bother to search before posting. Your post was a conscious effort to start a new thread on the same topic.


Quote:

The assumptions are not shaky at all. Have you ever heard the direct path?

Yes, I've heard headphone directly from a line-out, and the sound was not good. Not only was it not good, but it was clearly not the "unaltered original signal" -- dynamics were missing, bass was not being reproduced properly, etc. etc. These aren't things that an amp can add to a signal; only things that can be taken away by an inadequate source.

For all the reasons explained in the thread you referenced (Wodgy made many good points), I think your personal experiment must have been a freak success based on a perfect match between your source and your headphones, because I haven't been able to duplicate it

 

[JaZZ]

MacDEF
Quote:

Yes, I've heard headphone directly from a line-out, and the sound was not good. Not only was it not good, but it was clearly not the "unaltered original signal" -- dynamics were missing, bass was not being reproduced properly, etc. etc. These aren't things that an amp can add to a signal; only things that can be taken away by an inadequate source. For all the reasons explained in the thread you referenced (Wodgy made many good points), I think your personal experiment must have been a freak success based on a perfect match between your source and your headphones, because I haven't been able to duplicate it

I have the feeling that you totally misinterpret my statements. I wasn't pretending the direct-path sound is better. But my tests have shown that it's the sonic truth, and none of your objections concerning voltage-supply and impedance-matching issues are involved, and this with two different sources. What do you criticize on my test procedure? You don't mention to have done similar tests; your findings seem to be based on a completely subjective rating instead.

What I mean: You're highlighting some admittedly valid critical arguments and keep on ignoring my tests which take those into consideration... (repeatedly, you remember?)...

 

[AdamP88]

I'm not quite sure how you've come to the conclusion (from your tests) that direct path is the "sonic truth" compared to amps. How so?

Were you able to hear the same amount of details, or comparable imaging and layering to your amp? Was tonal accuracy comparable? Or are these just "euphonic" and "coloring" characteristics of headphone amps?

Given the fact that every amp you used seemed to improve the overall sound of the source, even if it might be euphonic coloring, wouldn't that be the preferable way, considering that listening to the direct path gives you a much less involving sound - a sound that in comparison is dry? You even said yourself, that listening through an amp makes the music more lifelike. Isn't THAT closer to the sonic truth?

 

[JaZZ]

Quote:

Originally posted by AdamP88 I'm not quite sure how you've come to the conclusion (from your tests) that direct path is the "sonic truth" compared to amps. How so? Were you able to hear the same amount of details, or comparable imaging and layering to your amp? Was tonal accuracy comparable? Or are these just "euphonic" and "coloring" characteristics of headphone amps?

Listning to music through my amp while having the same time a headphone switched parallel to the amp on the line-out made no clear sonic difference compared to unplugging the headphone. So the complex load represented by the headphone had virtually no impact on the sound - this tested with two DACs -, and the voltage supply was no issue.

Quote:

You even said yourself, that listening through an amp makes the music more lifelike. Isn't THAT closer to the sonic truth?

I can't follow your arguments. Why should this thus be closer to the sonic truth in this context where I'm explicitly not searching for ideal euphonic synergy and reconstruction of a credible sound, but the original sound how it is on the recording or provided by the CD player, resp.?

 

[lini]

JaZZ: "You can find my test configuration which has lead my to my conclusion in this thread, among others. The assumptions are not shaky at all. Have you ever heard the direct path? Have you systematically compared it to some amps? Choose a source from which you know it has low output impedance. Listen through an amp, plug and unplug some (preferrably high-impdance) headphone to the source parallel to the amp (with a splicer/adapter) and try to verify if there's a considerable change caused by the «complex load» (represented by the headphone). There was barely any in my case. This proofs that the direct path represents more or less the original sound. The theoretical objections regarding voltage supply and impedance matching are also covered by the mentioned test configuration, so the conclusion is absolutely justified."

Uhm - this only proves that in your case the direct path doesn't disturb the indirect path (or only a tiny bit...), but it won't prove that the direct path is closer to the original (= the headphone could still be not well driven in the direct path), I fear. Anyway, of course, if one hapens to have a good source with comparatively juicy output, it is always worth a try to drive a headphone directly and check the results...

Greetings from Munich!

Manfred / lini

 

[Solude]

Sigh, people need to get the word AMP out of their head. They are not anything more than a duplication of what is already in the source with the addition on an attenuator.

Fact, most sources have power supplies that make headphone amp power supplies look gimpy.

Fact, most op amps used in headphone amp are the same ones found in sources.

Fact, most sources provide far more voltage and current capability than a headphone, K1000 excluded, will ever use.

So you're telling me that the same op amp used with a beefier power supply providing more power than you'll ever use is not capable of competing with the sound of that same op amp with a lesser power supply but higher gain? Cute

 

[Gallaine]

Quote:

Originally posted by JaZZ And that's actually the main merit of the direct path: to show the actual behavior of headphone amps and - maybe to the regret of some people - their demystification and demythification! Are the best sounding ones also the most accurate ones? I really doubt it: the sound from the direct path is unspectacular in comparison. The most accurate amp would have to sound unspectacular as well. The reason (no completeness and absoluteness of validity intended): preserved dynamic means less direct appeal.

I am very confused. I thought the goal of most, maybe not all, systems was to reproduce a signal as close to the live event as possible i.e. the system reproduces music in a manner that convinces me I am listening to a live event. Therefore, a more accurate reproduction should not be "unspectacular" unless the live performance itself was unspectacular. The last time I sat in the audience for the local symphony orchestra it certainly was not lacking in excitment! Granted some music is created electronically and so doesn't really have a "live" representation.

It seems from your post that accuracy is with respect to the data on the media and not the event itself. Is that true? If you mean accuracy in the sense that it corresponds to the actual event recorded then how do you reconcile the aparent contradiction that an accurate signal is unpleasing? I suppose that you could argue that accuracy with respect to the data is also accuracy with respect to the recorded event. But that only leads us back to my question about the contradiction.

I'm not trying to "poop" on your parade. I just want to understand exactly what you are saying.

 

[bangraman]

"So is the whole direct-path debate superfluous?"

It is, isn't it? Any amp introduces further colouring to the colour added by the source, which in turn has colouring added by the mixing console at the studio, and before that the live mixing console and the mics. And all through this the studio engineer is adding or adjusting levels and effects based on his studio monitors which will also colour the original recording. Any attempt at genuine accuracy is completely futile I would have thought. You (or at least I) choose amps for the colour, sense of detail, soundstage, etc that you like best. It may be 'like being there' but the two in reality are unlikely to have much correlation even if you go direct.

 

[minya]

Quote:

Originally posted by JaZZ But my tests have shown that it's the sonic truth,

Huh? The "sonic truth"? I've tried the "direct path" and it sounds like, well, **** - like MacDEF said - no bass, fuzzy treble, etc. Not fun to listen to. At all.

If your opinion is that the "sonic truth" is garbage, then I guess we'll agree to disagree.

- Chris

 

[JaZZ]

Solude...

Quote:

Fact, most sources have power supplies that make headphone amp power supplies look gimpy. Fact, most op amps used in headphone amp are the same ones found in sources.

...thanks! That's exactly what I wanted to hear...

I was about to suspect that line-out stages are not that different from headphone amps when it comes to any sort of «control» with driving a headphone. This as a reply to lini's objection, which is a good one: The only doubt remaining after my tests is if a line-out-stage amp can control the drivers as well as a headphone amp does. I guess as long as the output impedance is in a comparable range and there's enough current supplied, the «control» should not be different to the headamp. That said I think the only control worth mentioning is back EMF around the resonance frequency. BTW, Wodgy, mentioned by McDEF, uses a line-out amp as headphone amp in his portable DAC.

 

[aos]

My Sostenuto-1 uses line amp that doubles as headphone amp. I am of opinion that what makes good line amp makes good headphone amp too. Ability to handle high capacitive / inductive loads, and serve lots of current, at low distortion and without breaking a sweat. So in this case you actually ARE listening to line-out when you plug in the headphones.

On the other hand, most line outs are driven directly by a regular opamp. While the opamp is typically capable of supplying few tens of mA of current and therefore can drive headphones, headphones are indeed a hard load (or complex if you want, although complex applies to the fact that it has resistance, inductance and capacitance so the total impedance is a complex number with real and imaginary part when used in AC analysis). And most opamps cannot handle hard loads very well. They prefer to drive high impedance purely resistive loads (say 1k or more) in order to provide their perfomance numbers such as distortion. Not only distortion would rise by driving headphones but additional thermal effects that are not typically measured and shown would kick in. Some opamps handle it better, some not. You basically have a CMOY if you're driving headphones from line out. Connect headphones in parallel with some RCA cables, plug them in your sound card and fire up RMAA and measure it. I bet you will see much inferior numbers with headphones plugged in, getting much worse as you keep plugging in lower and lower impedance phones.

Some DACs have beefed up line outs that could handle small speakers, let alone headphones. But those are not your typical CD players. So you can't make any kind of conclusion without knowing what is inside. If you're operating line out outside of its design specs you are not getting "naked" sound, you're getting unexpected sound.

 

[JaZZ]

Gallaine...

...yes, with accuracy I mean an unaltered signal from the CDP's line-out to the headphone drivers. Although it's massively doubted by a lot of people, the source sound is less appealing than they would have expected, according to my experiments and to my ears. I understand the doubts, but they don't prove anything. I guess people who renounce the pre-amp in their speaker setup (like me, too) could tell you some similar stories. But without a doubt it's faster, more transparent and more dynamic than after processing by an additional amplification stage. This is what I've experienced.

That doesn't mean I prefer the naked truth to a more euphonic and after all even more natural sound provided by the synergy a good amp can build up in each case. It sounds paradox, I know. But the crucial point could be the digital technique. Maybe it just needs some masking by euphonic harmonic distortion or whatsoever to sound enjoyable.