[miceblue]

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So, essentially, as long as you have enough power to properly amplify your headphones, nothing else really matters?
 
i.e. If someone has their headphones plugged directly into a PC motherboard with on-board sound, as long as that mobo has enough power to properly amplify the headphones, there's no reason to get a separate amp and DAC?  

 
And the big question (hence me asking earlier in the thread) was properly amplifying.  I think this is where some people get confused a little too.  From what I have learned - properly amplifying is sometimes confused as only being about volume.  My iPhone at ~ 70% will actually get my K701s and Q701s loud enough.  Heck at 90% volume it will get my 600 ohm DT880s loud enough as well.  But using an under-powered source can cause havoc with the frequency response.
 
That's why I wanted to check on a portable amp that would drive the K701 "well enough".

Ah, and this is where I get confused. When enough volume ≠ "proper" amplifying.

 

[bigshot]

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My iPhone at ~ 70% will actually get my K701s and Q701s loud enough.  Heck at 90% volume it will get my 600 ohm DT880s loud enough as well.

 
90% is pushing it, but at 70%, amping isn't going to improve things a heck of a lot. That's about like my Sennheiser HD590s. I used them with my iPod and they sounded fine at around 70%, but I wanted to see what amping them would do, so I bought a nice little cmoy. There might have been a tiny difference... I really couldn't test carefully enough to tell for sure... but even if there was, it wasn't enough to matter. The cmoy is in a drawer somewhere now. Who needs to carry around another battery operated box that does nothing?

 

[Brooko]

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90% is pushing it, but at 70%, amping isn't going to improve things a heck of a lot. That's about like my Sennheiser HD590s. I used them with my iPod and they sounded fine at around 70%, but I wanted to see what amping them would do, so I bought a nice little cmoy. There might have been a tiny difference... I really couldn't test carefully enough to tell for sure... but even if there was, it wasn't enough to matter. The cmoy is in a drawer somewhere now. Who needs to carry around another battery operated box that does nothing?

 
With headphones like Grados, SRH 840, even my HD600s (although they do seem to 'scale' better than the Grados/Shures), I'd agree.  But there is a definite and noticeable change with both the AKGs and the Beyers.  They Beyers in particular have very different sounding bass.  I know it's not damping factor (iPhone is a great source with low impedance) - so can only surmise that they aren't getting enough voltage (DT880) or current (AKG) - ie not being driven properly.
 
I'd be generally surprised if most people couldn't tell the difference between the Beyers & AKGs (amped properly vs amped by low power source only).  It's pretty noticeable.  Once again - the volume is fine (approaching the limits of the DAP's output) - but the frequency response of the headphone is right off.  I have no equipment to measure it - but I guess that's being under-driven?
 
Not sure on the science behind it - not enough to move the diaphragm properly?

 

[bigshot]

Well, that is a function of the design of the headphones, not the player. I wouldn't use STAX without an amp. But most headphones do fine straight from the jack of an iPod or iPhone. Besides, the iPhone is designed as a portable device to be used on the go. It's optimized for that, not big inefficient home cans. At home, it would be expected to dock it with a receiver or something and use the headphone out from that.

 

[Meremoth]

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Ah, and this is where I get confused. When enough volume ≠ "proper" amplifying.

 
 
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I'd be generally surprised if most people couldn't tell the difference between the Beyers & AKGs (amped properly vs amped by low power source only).  It's pretty noticeable.  Once again - the volume is fine (approaching the limits of the DAP's output) - but the frequency response of the headphone is right off.  I have no equipment to measure it - but I guess that's being under-driven?
 
Not sure on the science behind it - not enough to move the diaphragm properly?

 
Yes, this is exactly what I want to know.
 
If your amp gets your headphones plenty loud enough, how can you tell if they're still not being properly driven?
 
From a completely objective stand-point, is there any compatibility charts for amps and headphones?

 

[Joe Bloggs]

Actually, the volume at which a player or amp drives headphones is almost completely dependent on the maximum gain that can be set, not its actual voltage or current capability (unless the amp is distorting beyond recognition!).  You can have a very capable amp section that is limited by a low gain (e.g. to comply with safety stipulations).  The Wolfson chips on certain models of Samsung S phones is an example of this, they are like Ferraris with an electronic 100km/h speed limiter.  With apps like Voodoo sound you can unlock their gain setting and drive bigass orthos LOUD.
 
On the other hand, it's totally possible set a ton of gain on an amp that has so little actual current and voltage capability that it would clip with any headphone past the 30% mark... however this is rare.

 

[bigshot]

The easiest way to tell if you have an impedance problem is to rack up the same CD on a home stereo receiver and your iPhone in lossless, balance the volumes and see if one sounds better than the other. Most of the time, they should be the same.

 

[Meremoth]

So I'd assume there would be no type of problems with say, the LCD-3 and the O2/ODAC combo?  
 
Or I guess a better question would be, are you getting the absolute most out of your LCD-3's and music with the O2 + ODAC?
 
Also, is there any benefit not having the O2 and ODAC in the same enclosure?  

 

[Brooko]

Thanks Bigshot - that's what I was trying to say.  Of course I can only match volume by ear (don't have an SPL meter) - but on the NFB-12 vs the iPhone, with my AKG and Beyer, the desktop amp definitely sounds better to these old ears.  Even the HD600 upper register sounds slightly better.  But the Grados / Shures - sound pretty much the same to me.
 
I found this - and I think this nails why - can anyone advise if this is on the right track:
 

CLIPPING: When the source doesn’t have enough voltage and/or current to meet the peak demands of the music it clips off the peaks. Studies have shown it may go unnoticed if it’s infrequent and mild. But if it happens often, or a single event is severe, it tends to be plainly audible as a harsh “grunge”. It’s the number one cause of plainly audible distortion in everything from cell phones to car stereos. In the waveform shown to the right the yellow trace is properly reproduced while the green trace is from a less capable amp and you can see what happens to the peaks in the music—they’re “clipped” off as if someone took scissors to the music.

 
So could it be that their simply isn't enough oomph to drive the peaks with the AKG & HD600?
 
With the DT880 though - it tends to be more the bass - kind of loose, flabby and not well defined.

 

[miceblue]

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Thanks Bigshot - that's what I was trying to say.  Of course I can only match volume by ear (don't have an SPL meter) - but on the NFB-12 vs the iPhone, with my AKG and Beyer, the desktop amp definitely sounds better to these old ears.  Even the HD600 upper register sounds slightly better.  But the Grados / Shures - sound pretty much the same to me.
 
I found this - and I think this nails why - can anyone advise if this is on the right track:
 

CLIPPING: When the source doesn’t have enough voltage and/or current to meet the peak demands of the music it clips off the peaks. Studies have shown it may go unnoticed if it’s infrequent and mild. But if it happens often, or a single event is severe, it tends to be plainly audible as a harsh “grunge”. It’s the number one cause of plainly audible distortion in everything from cell phones to car stereos. In the waveform shown to the right the yellow trace is properly reproduced while the green trace is from a less capable amp and you can see what happens to the peaks in the music—they’re “clipped” off as if someone took scissors to the music.

 
So could it be that their simply isn't enough oomph to drive the peaks with the AKG & HD600?
 
With the DT880 though - it tends to be more the bass - kind of loose, flabby and not well defined.

I actually don't know what clipping sounds like for a headphone. I know what clipping sounds like in the sense of a recording, but not for headphones. I don't think a looser-sounding bass has to do with clipping though.
 
 
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So I'd assume there would be no type of problems with say, the LCD-3 and the O2/ODAC combo?  
 
Or I guess a better question would be, are you getting the absolute most out of your LCD-3's and music with the O2 + ODAC?
 
Also, is there any benefit not having the O2 and ODAC in the same enclosure?  

O2/ODAC should be fine since they can drive an LCD-2 just fine.
As I mentioned in my first post though, people often say "amp A sounds better than amp B since it has 2X the power so the LCD's really "sing" when they have a "good" amp powering them." I've read a lot of comments like this for the LCD-2. :rollseyes:

 

[uchihaitachi]

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So I'd assume there would be no type of problems with say, the LCD-3 and the O2/ODAC combo?  
 
Or I guess a better question would be, are you getting the absolute most out of your LCD-3's and music with the O2 + ODAC?
 
Also, is there any benefit not having the O2 and ODAC in the same enclosure?  

The enclosure shouldn't make any difference. 

 

[mikeaj]

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So could it be that their simply isn't enough oomph to drive the peaks with the AKG & HD600?
 
With the DT880 though - it tends to be more the bass - kind of loose, flabby and not well defined.

 
Which AKG, which version DT 880? Which iPhone version?
 
If you set iPhone or most integrated DAC/amp systems to max volume, they really shouldn't be clipping on high impedance loads, unless some idiot configured the thing. Many won't even into ~32 ohms or so, where the current demands are much higher. iPhone 5 doesn't and still has low distortion at the full-scale 1 V (rms) output:
http://www.kenrockwell.com/apple/iphone-5/audio-quality.htm
 
So it's not out of voltage or current.
 
The highest a peak could go is 1 * sqrt(2) = 1.41 V, the 0 dBFS (full scale) level. (2.82 V peak-to-peak). No matter what the input is. That happens when the music reaches 0 dBFS and you have it on max volume.** If you set it, it will happen... Oh yeah, before anybody asks about the distortion into real 32 ohm headphones, that's largely a result of the ~4 ohms output impedance. And, as noted, less than the distortion produced by the headphones themselves.
 
** okay, it's possible to go over 0 dBFS by a little bit between samples... cut me some slack

 

[Meremoth]

 

The enclosure shouldn't make any difference. 

 
 
I've heard that stacking certain amps and dacs on top of each other can cause audible interference of some kind.
 
 
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O2/ODAC should be fine since they can drive an LCD-2 just fine.
As I mentioned in my first post though, people often say "amp A sounds better than amp B since it has 2X the power so the LCD's really "sing" when they have a "good" amp powering them." I've read a lot of comments like this for the LCD-2. :rollseyes:

 
 
But I keep hearing that the LCD-3's are more "picky".
 
When I was thinking about getting the WA7 with the LCD-3's, I was told: 
 
 

From ears I trust, the WA7 works very well with the LCD-2s. But that said, the LCD-3s are harder to driver properly to get the most out of them. As well, the WA7 puts out a max of 1 W into 32 ohms. Not really ideal. I would say about 2 W (or more) into 50 ohms would be more ideal.
 

 
Would this be an issue with the O2/ODAC + LCD-3's?  
 
I'm no longer considering a tube amp, BTW, because it seems like solid state can be somewhat superior and/or more neutral/flat/without coloration?  Are there any neutral tube amps?  I guess there would be no point in getting a neutral tube amp, huh?  If you were to do that, it'd make more sense in getting a SS, right?  Is there any reason to have a tube amp other than for coloration?  

 

[Joe Bloggs]

You could take a look at this chart
http://www.head-fi.org/t/668238/headphones-sensitivity-impedance-required-v-i-p-amplifier-gain
and then compare with the specs of the amp you want to get

 

[Brooko]

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Which AKG, which version DT 880? Which iPhone version?
 
If you set iPhone or most integrated DAC/amp systems to max volume, they really shouldn't be clipping on high impedance loads, unless some idiot configured the thing. Many won't even into ~32 ohms or so, where the current demands are much higher. iPhone 5 doesn't and still has low distortion at the full-scale 1 V (rms) output:
http://www.kenrockwell.com/apple/iphone-5/audio-quality.htm
 
So it's not out of voltage or current.
 
The highest a peak could go is 1 * sqrt(2) = 1.41 V, the 0 dBFS (full scale) level. (2.82 V peak-to-peak). No matter what the input is. That happens when the music reaches 0 dBFS and you have it on max volume.** If you set it, it will happen... Oh yeah, before anybody asks about the distortion into real 32 ohm headphones, that's largely a result of the ~4 ohms output impedance. And, as noted, less than the distortion produced by the headphones themselves.
 
** okay, it's possible to go over 0 dBFS by a little bit between samples... cut me some slack

 
Hi Mike
 
The iPhone is a 4 (arguably the lowest impedance iPhone they released)
The AKGs were K701s
The Beyers were DT880 600 ohm
 
Sorry for all the questions - I'm just trying to understand what effect there are in under-powering headphones.
 
I can understand clipping - not achieving the volume peaks, and guess this will be represented by audible distortion.
 
How does this effect the bass though (on the DT880).  Audibly - if I try to describe the difference I hear (between NFB-12 and iPhone) - on the iPhone the bass sounds weak, loose and somewhat flabby (sorry - but west way I can describe it).