[PhoenixG]

   
Whether the term "balanced" is misleading or not is mostly a matter of context. Historically, in the days of tube equipment, very little equipment was internally balanced (although "push-pull" is a form of balanced design). However, because of the higher operating impedances of tube equipment, the connections between equipment were very sensitive to picking up hum and noise. Therefore, in the old days, most pro tube equipment used small signal transformers at the outputs and inputs to "create" a balanced signal for connection purposes. Good quality transformers worked very well for this, but were quite expensive, and so a good quality balanced input or output was considered an important premium feature on pro equipment - and one that you often paid a lot extra for - even though nobody even asked whether the rest of the circuitry was balanced or not (and it probably wasn't).
 
The thing you really need to keep in mind, though, is that all of this is done in the service of performance. (For example, if your DAC device has a S/N of 110 dB, which is excellent, it really doesn't matter if the Wolfson chips inside it are connected in the mode that gets a S/N of 125 dB or the mode that gets 128 dB. In a DAC, how well the power supply is designed, and how carefully the circuitry is laid out, will usually make much more difference than which mode on the chip is used.) If you have an unbalanced connection, and it's picking up noise, then switching to a balanced connection will probably help; and, if you're just putting together a system, using balanced connections to begin with will make it less likely that you'll have a noise problem; but, if you have unbalanced connections, and they're dead quiet already, then switching to balanced connections is unlikely to make any difference. Likewise, all else being equal, a balanced design may have lower distortion, but all else is rarely equal, so all that really counts in the end is the performance itself (it's quite possible for a well designed non-balanced amplifier to perform better, and sound better, than a balanced one that is less well designed).

Thanks for the history lesson! I really enjoy when audio dogma is put into perspective. I think you hit the nail on the head for this one. There are a lot of traps we audiophiles are led to to spend our $$$ on things that objectively make no audio difference. Sure something may be 'better', but is it worth it? Often the answer is no. It's like looking at a picture of the stars and saying "ah yes, Alpha Centauri is definitely 4  lightyears away in this one, not 10." Maybe a carefully calibrated machine could tell the difference if it were hooked up to the equipment that took it, but not only can I not, it is beyond impossible for any human to.
 
The second trap you hit on was the old $20 saddle on a $5 horse. You can spend infinite amounts on cables, power conditioners, interconnects, magic garbage, room treatments, jumpers, etc., but you've wasted it if your amp isn't well done with a good source and good speakers/phones. There is a cost/benefit to everything that seems to often get kinda bonkers. I saw a really cool system once (ML1C w/ jbl horns, MC275, beautiful) and the guy had a room that was really noisy. It's hard to even tell if it sounds good when your curio cabinet jangles, and throwing all the cables you want at it won't fix that.

 

[SirMarc]

Thanks for the history lesson! I really enjoy when audio dogma is put into perspective. I think you hit the nail on the head for this one. There are a lot of traps we audiophiles are led to to spend our $$$ on things that objectively make no audio difference. Sure something may be 'better', but is it worth it? Often the answer is no. It's like looking at a picture of the stars and saying "ah yes, Alpha Centauri is definitely 4  lightyears away in this one, not 10." Maybe a carefully calibrated machine could tell the difference if it were hooked up to the equipment that took it, but not only can I not, it is beyond impossible for any human to.

The second trap you hit on was the old $20 saddle on a $5 horse. You can spend infinite amounts on cables, power conditioners, interconnects, magic garbage, room treatments, jumpers, etc., but you've wasted it if your amp isn't well done with a good source and good speakers/phones. There is a cost/benefit to everything that seems to often get kinda bonkers. I saw a really cool system once (ML1C w/ jbl horns, MC275, beautiful) and the guy had a room that was really noisy. It's hard to even tell if it sounds good when your curio cabinet jangles, and throwing all the cables you want at it won't fix that.

That's funny, the guy I bought my dynaco from was bragging about his system, and brought me up to hear it. He had very nice stuff, a fisher tube receiver, a linn TT, and some other nice gear, but he had one speaker right in the corner with no toe in, and the other speaker halfway down the wall and angled about 45 degrees. It sounded horrible lol

 

[MP1968]

Don't wish to derail the thread, but having read a lot of it in the past few weeks I thought I'd post my comparisons of an SA-9100 with a Master 9.
 
Firstly, I'll thank Oregonian who took the time to answer some questions I had on vintage gear and nudged me over the edge into buying the SA-9100.  This was sold to me by someone who has refurbished 6 of these already, and I understand is known on AudioKarma for his work.  So I'm confident that all the recapping and whatnot has been done well.  
 
In its own right I've been very pleased with it as a headphone amp, but in the past couple of weeks I've had a few listening sessions to try and tease out the differences between the 9100 and my Master 9.  This has largely been done with TH900s, although this evening I tried my LCD XCs as well. For information, my general tastes are rock: Royal Blood, Rival Sons, Band of Skulls, Arctic Monkeys, etc etc.  
 
And quite honestly the differences between the two amps aren't very obvious: it takes a lot of back and forth between the two to work out what they are.  With the TH900s the 9100 hits a little harder in the bass and the lower end of the mid range, but not overwhelmingly so.  The Master 9 is a touch crisper, probably because I detect a little more presence in the treble.  The soundstage is possibly very slightly wider on the M9 on some tracks: difficult to be certain.  
 
But what the 9100 does have is a sort of propulsion to the music: it gets my toes tapping, there's a bit more meat on the bones of the music.  I don't know whether this is anything to do with the output impedance of the 9100 which I assume is somewhere in the 100-300 ohm range which I've been told that many of these vintage amps have, versus the 1 ohm or so of the M9.  The TH900s aren't insensitive 'phones.  
 
So, I'm very impressed.  Much as I've enjoyed the M9, and had regarded it as my endgame amp, it may be appearing in the for sale forum at some point.
 
Then finally, the TH900s versus the XCs out of the 9100..................... I prefer the TH900s.  I find the XCs to be warmer phones (certainly compared to the LCD3s which I had until recently), and it's too much for me when added to the slight warmth of the 9100.  The XCs sound almost a bit sluggish, whereas the TH900s retain a crispness and attack which works for the type of music I like.  
 
Anyway, hopefully this'll be of interest to a couple of people.  

 

[jnorris]

I have always felt that the prodigious gobs of current instantaneously available from a receiver/integrated amp/amplifier renders far more dynamics and presence that the current-starved tube/op-amp/discrete crop of headphone-specific amps.  And if you thought the Pioneer sounded good, you should hear some of the more respected names in components.  MacIntosh, Denon, and NAD spring to mind.

 

[Rossliew]

Agreed. Currently listening with my NAD 3020 - lovely, lovely amp. Costs a mere fraction of the current crop of headphone amps yet delivers gobs of power and dynamics unrivalled by any head-amp i have (cost vs performance wise). I do notice however that the headphone jack favours cans of the higher impedance variety (something about the higher output impedance which i read somewhere).

 

[SirMarc]

Did any of you guys jump on the HD 598 black Friday deal on Amazon? Holy crap! After some break in, I really like these headphones. The only thing that sucks is they're only 50 ohms, so they're not playing well with my 9090. That's ok though, they sound fantastic with my Asgard 2, and surprisingly good out of my phone and tablet. I just have the Asgard 2 running off the tape out from the 9090.
The other good thing is they're black, as opposed to the cream and brown color scheme that I never liked. I think I'm starting to like them more than my HD580's. Best 94 bucks I've spent in a while...

 

[Benny-x]

 
But what the 9100 does have is a sort of propulsion to the music: it gets my toes tapping, there's a bit more meat on the bones of the music.  I don't know whether this is anything to do with the output impedance of the 9100 which I assume is somewhere in the 100-300 ohm range which I've been told that many of these vintage amps have, versus the 1 ohm or so of the M9.  The TH900s aren't insensitive 'phones.  
 
So, I'm very impressed.  Much as I've enjoyed the M9, and had regarded it as my endgame amp, it may be appearing in the for sale forum at some point.
 
Then finally, the TH900s versus the XCs out of the 9100..................... I prefer the TH900s.  I find the XCs to be warmer phones (certainly compared to the LCD3s which I had until recently), and it's too much for me when added to the slight warmth of the 9100.  The XCs sound almost a bit sluggish, whereas the TH900s retain a crispness and attack which works for the type of music I like.  
 
Anyway, hopefully this'll be of interest to a couple of people.  

  Agreed. Currently listening with my NAD 3020 - lovely, lovely amp. Costs a mere fraction of the current crop of headphone amps yet delivers gobs of power and dynamics unrivalled by any head-amp i have (cost vs performance wise). I do notice however that the headphone jack favours cans of the higher impedance variety (something about the higher output impedance which i read somewhere).

Did any of you guys jump on the HD 598 black Friday deal on Amazon? Holy crap! After some break in, I really like these headphones. The only thing that sucks is they're only 50 ohms, so they're not playing well with my 9090. That's ok though, they sound fantastic with my Asgard 2, and surprisingly good out of my phone and tablet. I just have the Asgard 2 running off the tape out from the 9090.
The other good thing is they're black, as opposed to the cream and brown color scheme that I never liked. I think I'm starting to like them more than my HD580's. Best 94 bucks I've spent in a while...

 
So, I've kind of purposely avoided the impedance matching and whatnot topic for a while since I have no idea about it. But here you guys are all talking about it about headphones on speaker equipment, so can anyone kind of lay it out for me? How does it work, what matters, what's supposed to match well, and what's supposed to cause problems? I heard this impedance thing is why sometime a PREamp can sound better than DAC(with digital volume or integrated PRE) to amp direct, because the PRE sorts out impedance issues.
 
I plan on using headphones from one of these receivers, but I've heard I will need to use one of those "Can Opener" adaptors or like the HiFiMAN kit for converting speaker taps to 4pin XLR. I'd also like to try XLRs/RCAs over to my active speakers. 
 
And for headphones, I've got JVC DX-1000, Audeze LCD 2.2, and Sennheiser IE-8 IEMs. I know they all have different impedances and I've heard that whatever the Audezes have plays nicely off the speaker taps of a vintage receiver/integrated.
 
So, if anyone could lay it out for me and include a couple different connection scenarios I'd really appreciate it

 

[MP1968]

I'm not at all an expert on this, but you may find this Head Fi article useful:
 
http://www.head-fi.org/a/headphone-impedance
 
One of the key messages for me was 'As a rule of thumb, the load impedance (headphone) should be at least eight times higher than the amplifier output impedance'.  My TH900s are 25 ohms impedance, so according to this theory then the maximum output impedance of the headphone amplifier I use should be around 3 ohms.  My Master 9 is 1 ohm, so that obviously complies.  These vintage amps / receivers, however, output somewhere between 100 and 300 ohms through the headphone output which according to that article doesn't allow any damping factor.
 
At this point someone else will need to take over and give you more information, as I certainly don't understand the technicalities of all this.  All I could do was spend time comparing my TH900s out of my SA9100 and the M9, and try to work out what the differences are.  Not many, was my conclusion.  
 
I don't know about running LCD2s directly off amplifier speaker taps, but many Hifiman HE6 owners certainly do.  I think this is less to do with their impedance (I think it's around 50 ohms) and more to do with their low sensitivity (I recall around 83 dB/mW).   

 

[jnorris]

   
So, I've kind of purposely avoided the impedance matching and whatnot topic for a while since I have no idea about it. But here you guys are all talking about it about headphones on speaker equipment, so can anyone kind of lay it out for me? How does it work, what matters, what's supposed to match well, and what's supposed to cause problems? I heard this impedance thing is why sometime a PREamp can sound better than DAC(with digital volume or integrated PRE) to amp direct, because the PRE sorts out impedance issues.
 
I plan on using headphones from one of these receivers, but I've heard I will need to use one of those "Can Opener" adaptors or like the HiFiMAN kit for converting speaker taps to 4pin XLR. I'd also like to try XLRs/RCAs over to my active speakers. 
 
And for headphones, I've got JVC DX-1000, Audeze LCD 2.2, and Sennheiser IE-8 IEMs. I know they all have different impedances and I've heard that whatever the Audezes have plays nicely off the speaker taps of a vintage receiver/integrated.
 
So, if anyone could lay it out for me and include a couple different connection scenarios I'd really appreciate it

Most receivers have a headphone jack, so you needn't worry about interfacing speaker taps with headphones.  As for the impedance thing...
 
The great majority of receivers and amps that provide a headphone jack do so by dropping the speaker outputs through a 120 to 300 ohm resistor to limit the current into the headphone.  Some preamps run their outputs through an IC amp (almost always an NJM4556 - the same lackluster chip used in the Grado headphone amp) to provide a headphone amp, and at least one preamp feeds headphones directly from its line out stage.
 
The general consensus is that amplifiers need low output impedance because it is important to maintaining a high damping factor, thus allowing the amp to better control the back EMF (electro-magnetic force) from the drivers in the headphones.  My feeling is that high damping factor is important when the drivers are regular speakers with huge magnets that induce large back EMF currents, but the miniscule back EMF generated by the tiny magnets in a headphone have little or no effect on the amp.
 
So plug your headphones into your receiver and enjoy!

 

[SpeakerBox]

  Most receivers have a headphone jack, so you needn't worry about interfacing speaker taps with headphones.  As for the impedance thing...
 
The great majority of receivers and amps that provide a headphone jack do so by dropping the speaker outputs through a 120 to 300 ohm resistor to limit the current into the headphone.  Some preamps run their outputs through an IC amp (almost always an NJM4556 - the same lackluster chip used in the Grado headphone amp) to provide a headphone amp, and at least one preamp feeds headphones directly from its line out stage.
 
The general consensus is that amplifiers need low output impedance because it is important to maintaining a high damping factor, thus allowing the amp to better control the back EMF (electro-magnetic force) from the drivers in the headphones.  My feeling is that high damping factor is important when the drivers are regular speakers with huge magnets that induce large back EMF currents, but the miniscule back EMF generated by the tiny magnets in a headphone have little or no effect on the amp.
 
So plug your headphones into your receiver and enjoy!

 
+1 - he could try inserting his own (lower) HP Jack resistors if he wanted or just jumper them out to see how it sounds, but you are most likely correct as moving mass is lower too.  If you do eliminate the resistors watch the volume control as it will get louder faster.

 

[Skylab]

In addition to jnorris's excellent post, note that damping factor is irrelevant for the LCD-2, as the impedance curve is completely flat across the frequency spectrum.

 

[SpeakerBox]

In addition to jnorris's excellent post, note that damping factor is irrelevant for the LCD-2, as the impedance curve is completely flat across the frequency spectrum.

 
Since damping factor is load impedance divided by amplifier output impedance I think it means that the DF is constant across the spectrum rather than irrelevant.  It could still turn out that the actual DF number is unfavorable (doubt it but could be).
 
Am I missing something Skylab?

 

[analogsurviver]

   
Since damping factor is load impedance divided by amplifier output impedance I think it means that the DF is constant across the spectrum rather than irrelevant.  It could still turn out that the actual DF number is unfavorable (doubt it but could be).
 
Am I missing something Skylab?

Your reasoning is correct. Better damping factor means better control.
 
The most thorough treatment of headphone/impedance issues I have seen online is this : 
http://www.innerfidelity.com/content/musings-headphone-amplifier-output-impedance#lXxz1i8HoBHscGDw.97

 

[KeithEmo]

Absolutely correct.... but output impedance (damping factor) also affects frequency response, which is what i think they're getting at.
 
If your headphones have an impedance that varies widely, and your amplifier has a high output impedance (low damping factor), then, as well as not controlling the drivers well, the two will tend to interact to produce significant variations in frequency response. However, if the impedance curve of the headphones is relatively flat, then, even if the amplifier does have a high output impedance, while it won't control the headphones as well, you won't get that frequency response interaction.
 
 
Quote:

  Your reasoning is correct. Better damping factor means better control.
 
The most thorough treatment of headphone/impedance issues I have seen online is this : 
http://www.innerfidelity.com/content/musings-headphone-amplifier-output-impedance#lXxz1i8HoBHscGDw.97

 

[analogsurviver]

 

Both of what you mentioned is correct.
 
The biggest issue with headphones I have is the *sigh* TRS jack(s).  Any headphone should have 4 terminals - each channel  separately, no possibility of short circuiting the output of the amp when plugging or unplugging the headphones in or out.
 
No one would believe the sound something as lowly as Grado SR-60 can produce if driven right.  I have modified the output of the Perreaux SM2 preamp in order to be able to drive headphones - and after a couple of months of use, phone rang and I accidentally pulled out the TRS plug and one channel output went up in smoke - what else ?
 
I will repair it ( 300V output MOSFET by now rare as hell gave up the ghost  ) and re-terminate the thing with 4 pole XLR connector - to avoid that dreaded TRS short circuit.  I might even put a fuse(s) in series - but I try to avoid them whenever not absolutely required. SM2 has +-45 VDC power supply, so approx 30 VRMS output capability, is pure class A, has power supply bank greater than most power amps - and should be the dream amp for the AKG K-1000.
 
Sorry, no receiver will ever even dare to dream about this kind of performance...