[WiR3D]

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Too musical as in a loss of fidelity?

Both. The Denons are already musical (the king of Fun to boot) so adding tons more colouration is like adding jet fuel to a gasoline fire to put it out.

 

[boyfrombluesea]

Just bought Audio-gd NFB-11.32 to paired with my Denon D5000.
It sounds wonderful and neutral!
The highs being rolled-off just a little bit, makes it perfect.
Bass more tighter and refined.
I couldn't be more happy with the combination.

 

[songmic]

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Amps that DONT work

1. All OTL tube amps (with more then 3ohm output impedance): Decaware CSP-2
2. All Amps with higher then 2 ohm output impedance (3 ohm maximum for tubes)

1. ASUS Xonar Essence ST/X (Only those who don't know any better like it.)
2. BottleHead Crack (OTL)
3. DarkVoice 336 (OTL)
4. Fiio E7 (Does not provide enough current)
5. Fiio E9 (1 for, many against)
6. Little Dot (MKI+ [32 ohm output impedance] ...)
7. Nuforce anything (all 10ohm and coloured)
8. Schiit Valhalla (Tubes)
9. SPL Auditor (made for High Voltage)

1. Woo Audio WA22, WA2, WA6 (Tubes)

 
I understand your concern regarding the use of tube amps, especially OTL tube amps with the Denons, but I beg to differ. I own a Fostex TH900, but it is nearly identical to the D7000 in terms of specs (impedance, sensitivity, design, sound signature, etc.). So let's take the D7000 for example.
 
I believe your rationale is that the D7000 is a low impedance headphone, so one would need an amp with low output impedance (which most solid-state amps are but tube amps aren't) to ensure enough damping factor to control the drivers and reduce distortion. I completely get that. However, there's something special about the D7000 (and the TH900, for that matter). We say the D7000 has an impedance of 25 ohms, but to be precise, it is 25 ohms at 1kHz. The reason we use the term "impedance" and not "resistance" is because headphones have varying resistant value depending on the sound frequency delivered. This is what impedance means, and why we need to consider looking at the impedance curve. In the link provided below, the impedance curve is the second graph from the left.
 
http://www.innerfidelity.com/images/DenonAHD7000.pdf
 
As you can see, the impedance curve is mostly flat, and the highest at 40Hz, at around 31 ohms. So the impedance variation would be 25 to 31 ohms. Compared to the HD800 (we are told it has an impedance of 300 ohms), which fluctuates between around 300 to 600 ohms, the D7000 can be said to have a very flat impedance curve.
 
http://www.innerfidelity.com/images/SennheiserHD800.pdf
 
And it is this variation in impedance that causes impedance-related distortions. The general acceptable amount of distortion, in other words variation, is 1 dB or below, which the human ears cannot discern. The formula for calculating this variation in dB is as follows: 20 * log[(Zmin+Zamp)*Zmax/(Zmax+Zamp)*Zmin], where Zmin is minimum impedance of headphone, Zmax is maximum impedance of headphone, and Zamp is the output impedance of the amp.
 
This result of this formula should be 1 or less to ensure there is no audible distortion caused by improper matching of impedance between headphone and amp. Due to the nature of this formula, the result becomes close to zero when 1. there is a large gap between Zmin (or Zmax) and Zamp, 2. there is a little gap between Zmin and Zmax, 3. the Zamp (output impedance of amp) is close to zero. Theoretically, if the impedance curve were ideally flay, meaning Zmin=Zmax, there would be completely zero distortion no matter how high the output impedance of the amp is. In other words, if the D7000 had a constant resistance of 25 ohms throughout all frequency range, you could connect it to a 100 ohm-output impedance OTL amp and still have no distortion whatsoever.
 
Because the Zmin = 25 and Zmax = 31 in D7000's case, there is a little gap between Zmin and Zmax. In such cases, the need to have a smaller output impedance of the amp becomes less important. If we were to drive it with a tube amp whose output impedance is 5 ohms, the result of the formula would show that the maximal distortion is only about 0.3 dB. At output impedance of 10 ohms, the distortion is about 0.5-0.6 dB. At output impedance of 30 ohms (which actually happens to be the "low" output impedance of WA6SE, your favorite amp with the D7000), the distortion is still around 1 dB or less.
 
So, there you have it. Although I would still advise against OTL tube amps whose output impedance are 50 ohms or higher, the D7000 is likely to work well with a wide range of transformer-coupled tube amps whose output impedance are 30 ohms or lower. Of course, there are other, much more important factors in proper matching of amp and headphones, but what I'm saying is that one would not need to worry about using tube amps in general only because they have higher output impedance than solid-states. If the D7000 had a very fluctuating impedance curve like the HD800, I would stay away from tube amps too. But as I've proved in above paragraphs, the relatively flat impedance curve of the D7000 allows it to be driven by many transformer-coupled tube amps without impedance-related distortion issues. If the D7000 sounds bad with a particular tube amp, it should be not because of damping factor but because of something else. Same goes for solid-state amps.

 

[WiR3D]

Quote:

*snip*

 bravo sir.
 
Their is one problem. Take a low impedance source and connect an output impedance increasing adapter in the chain and tell me if you notice the sound gets worse. Because I sure as hell do. The same can be said for taking a source with a modest 10ohms output impedance and connecting a faux output impedance decreasing adapter to into the chain, the sound improves. Mainly in the bass region, I suppose from dampening factor? 
 
And micro details are more evident, atleast to my ears, an in my completely unprofessional test.

 

[songmic]

Quote:

 bravo sir.
 
Their is one problem. Take a low impedance source and connect an output impedance increasing adapter in the chain and tell me if you notice the sound gets worse. Because I sure as hell do. The same can be said for taking a source with a modest 10ohms output impedance and connecting a faux output impedance decreasing adapter to into the chain, the sound improves. Mainly in the bass region, I suppose from dampening factor? 
 
And micro details are more evident, atleast to my ears, an in my completely unprofessional test.

 
I have a good explanation for that. First of all, I don't think what you're experiencing is a matter related to damping factor. It's more of a matter related to voltage distribution between two resistors connected in a single chain, where the two resistors are the headphone itself and the output of the amp. If the output impedance of the headphone amp increases, relatively more voltage is distributed to the headphone amp output while less voltage is distributed to the headphone. Although D7000 is a low impedance, high sensitivity headphone that depends more on current than voltage, the change in voltage can still affect its performance. The reason why you're seeing the improvement mainly in the bass region is probably because that's where the impedance of the D7000 is highest, at around 40Hz (take a look at the impedance curve and you'll see).
 
Now, I never said output impedance doesn't matter. In fact, I do think having a lower output impedance is always better than having a high output impedance if every other condition is the same. However, I did not say that an "amp" having lower output impedance is always better than an "amp" having a high output impedance. My point is that as long as the calculated distortion in dB is less than 1, you shouldn't worry whether the inherent output impedance of the amp is lower or higher than one another.
 
You see, in your experiment, you intentionally altered the output impedance of one same amp. Let's call this amp A. Of course the sound and the damping factor will be altered if you change the output impedance of amp A. However, this does NOT imply that amp B, which has an inherently lower output impedance than amp A, is always the better amp. Why? Because output impedance is not the only thing that is different with A and B. If all amps were designed the same way, the only difference being output impedance, then the obvious choice would be to choose the amp with the minimal output impedance to secure more damping factor and more voltage for the headphone. But in real life, there are countless, far more significant factors that determine the "matching" between an amp and a headphone. Factors that really do matter under the assumption that both amps provide a distortion of less than 1 dB.
 
Here's a good example: amp A has inherently higher output resistance than amp B. However, amp A also has inherently higher power and voltage output than amp B. In a non-comparison study with amp A alone, the sound will degrade if you intentionally increase its output impedance. Ditto for amp B alone. Which could lead one to believe than an amp having lower impedance is better than having higher impedance. However, when comparing A and B, it turned out that A sounded better. The reason was because A also had a inherently higher power output that made up for the relative loss of voltage distribution that goes to the headphone. See what I mean?
 
That is why damping factor, which is measured as headphone impedance divided by amp's output impedance, should only be used as a general rule of thumb. It is widely accepted that the damping factor should be greater than 8 (meaning the amp's output impedance should be lower than 1/8 of headphone impedance), but this is to ensure the headphones will get proper damping even when they have very fluctuating impedance curve. For relatively flat headphones like D7000, the required damping factor to ensure a distortion of less than 1dB is far less than the traditional 8, even going below 1 (the fact that WA6SE's 30 ohms output drives 25 ohms D7000 proves this point). What really matters is the equation:
 
Maximum dB variation = 20 * log [(Zmin+Zamp) * Zmax / (Zmax+Zamp) * Zmin]
(distortion caused by minimal and maximal impedance value throughout the sonic spectrum)

 

[preproman]

Good stuff.  However,  what is your preferred amp with the TH900s or the D7000s?

 

[songmic]

Quote:

Good stuff.  However,  what is your prefer ed amp with the TH900s or the D7000s?

 
For the TH900, Burson Soloist and Violectric V200 in the sub-$1K category. The former is clear and crisp (albeit sometimes dry) sounding, with excellent PRaT and bass quality, while the latter is warm, rich, and musical. I currently own the Soloist.
 
A decent tube amp is Yamamoto Soundcraft HA-02, I'm sure it will be a great match with the D7000 too.

 

[preproman]

Quote:

 
For the TH900, Burson Soloist and Violectric V200 in the sub-$1K category. The former is clear and crisp (albeit sometimes dry) sounding, with excellent PRaT and bass quality, while the latter is warm, rich, and musical. I currently own the Soloist.
 
A decent tube amp is Yamamoto Soundcraft HA-02, I'm sure it will be a great match with the D7000 too.

 
Did you sell the V200?

 

[songmic]

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Did you sell the V200?

 
I never owned the V200, but I heard it many times at local headphone meetings.

 

[WiR3D]

Quote:

 
 

Spoiler: Warning%3A%20Spoiler!

 
I have a good explanation for that. First of all, I don't think what you're experiencing is a matter related to damping factor. It's more of a matter related to voltage distribution between two resistors connected in a single chain, where the two resistors are the headphone itself and the output of the amp. If the output impedance of the headphone amp increases, relatively more voltage is distributed to the headphone amp output while less voltage is distributed to the headphone. Although D7000 is a low impedance, high sensitivity headphone that depends more on current than voltage, the change in voltage can still affect its performance. The reason why you're seeing the improvement mainly in the bass region is probably because that's where the impedance of the D7000 is highest, at around 40Hz (take a look at the impedance curve and you'll see).
 
Now, I never said output impedance doesn't matter. In fact, I do think having a lower output impedance is always better than having a high output impedance if every other condition is the same. However, I did not say that an "amp" having lower output impedance is always better than an "amp" having a high output impedance. My point is that as long as the calculated distortion in dB is less than 1, you shouldn't worry whether the inherent output impedance of the amp is lower or higher than one another.
 
You see, in your experiment, you intentionally altered the output impedance of one same amp. Let's call this amp A. Of course the sound and the damping factor will be altered if you change the output impedance of amp A. However, this does NOT imply that amp B, which has an inherently lower output impedance than amp A, is always the better amp. Why? Because output impedance is not the only thing that is different with A and B. If all amps were designed the same way, the only difference being output impedance, then the obvious choice would be to choose the amp with the minimal output impedance to secure more damping factor and more voltage for the headphone. But in real life, there are countless, far more significant factors that determine the "matching" between an amp and a headphone. Factors that really do matter under the assumption that both amps provide a distortion of less than 1 dB.
 
Here's a good example: amp A has inherently higher output resistance than amp B. However, amp A also has inherently higher power and voltage output than amp B. In a non-comparison study with amp A alone, the sound will degrade if you intentionally increase its output impedance. Ditto for amp B alone. Which could lead one to believe than an amp having lower impedance is better than having higher impedance. However, when comparing A and B, it turned out that A sounded better. The reason was because A also had a inherently higher power output that made up for the relative loss of voltage distribution that goes to the headphone. See what I mean?
 
That is why damping factor, which is measured as headphone impedance divided by amp's output impedance, should only be used as a general rule of thumb. It is widely accepted that the damping factor should be greater than 8 (meaning the amp's output impedance should be lower than 1/8 of headphone impedance), but this is to ensure the headphones will get proper damping even when they have very fluctuating impedance curve. For relatively flat headphones like D7000, the required damping factor to ensure a distortion of less than 1dB is far less than the traditional 8, even going below 1 (the fact that WA6SE's 30 ohms output drives 25 ohms D7000 proves this point). What really matters is the equation:
 
Maximum dB variation = 20 * log [(Zmin+Zamp) * Zmax / (Zmax+Zamp) * Zmin]
(distortion caused by minimal and maximal impedance value throughout the sonic spectrum)
 

 

I Cannot tell you how much I appreciate this write up. To summarize, that equation is what matters, and basicaly the amount of power the amp can supply is actually more important then output impedance, but both are related. So I was not too far off. I will update the first post to reflect that. and point them people to this post to explain. 
Quote:

 
For the TH900, Burson Soloist and Violectric V200 in the sub-$1K category. The former is clear and crisp (albeit sometimes dry) sounding, with excellent PRaT and bass quality, while the latter is warm, rich, and musical. I currently own the Soloist.
 
A decent tube amp is Yamamoto Soundcraft HA-02, I'm sure it will be a great match with the D7000 too.

This is also very useful. 
 
I'm going to make a few changes to the first post when I get time.
 
Many of us appreciate your input.

 

[songmic]

Quote:

To summarize, that equation is what matters, and basicaly the amount of poer the amp can supply is actually more important then output impedance, but both are related.

 
That's not always true. The power output of the amp is important in hard-to-drive, low sensitive headphones like K1000, HE-6, LCD-2/3, while less important in headphones with high sensitivity such as your D7000, my TH900, and our V-MODA M-100 (I signed up for pre-order too ). In sensitive headphones, what's more important than power output is the quality of the amplification and also the quality of the source/DAC.
 
Take this with a grain of salt, but some people, mostly fans of OTL amps, claim that having a high output impedance is preferable if one's using high impedance cans like Senns or Beyers. Driving 3-600 ohm cans with low output impedance solid-state amps will result in a *very* high damping factor, but the sound may become too thin and less musical/enjoyable.
 
For the record, the last OTL amp I owned was Little Dot Mk.III, which was a long time ago. My 600 ohm DT880 driven by LDMK3 was very clean sounding, one of the advantages that OTL amps provide in terms of clarity.

 

[KingHova]

What about the arcam rpac? I ordered this with the Denon D600 and it's set to arrive soon. Hope I haven't made a mistake ordering this :/

http://www.amazon.co.uk/DIGITAL-ANALOGUE-CONVERTER-HEADPHONE-AMPLIFIER/dp/B007NXM3K2/ref=sr_1_44?s=receiver-speakers&ie=UTF8&qid=1352734374&sr=1-44

 

[WiR3D]

Quote:

 
That's not always true. The power output of the amp is important in hard-to-drive, low sensitive headphones like K1000, HE-6, LCD-2/3, while less important in headphones with high sensitivity such as your D7000, my TH900, and our V-MODA M-100 (I signed up for pre-order too ). In sensitive headphones, what's more important than power output is the quality of the amplification and also the quality of the source/DAC.
 
Take this with a grain of salt, but some people, mostly fans of OTL amps, claim that having a high output impedance is preferable if one's using high impedance cans like Senns or Beyers. Driving 3-600 ohm cans with low output impedance solid-state amps will result in a *very* high damping factor, but the sound may become too thin and less musical/enjoyable.
 
For the record, the last OTL amp I owned was Little Dot Mk.III, which was a long time ago. My 600 ohm DT880 driven by LDMK3 was very clean sounding, one of the advantages that OTL amps provide in terms of clarity.

I will definitely reread your posts, its a lot of gold to dig through.
 
But again, thanks for your input - its much appreciated. 

 

[chewy45]

Quote:

Now i noticed that you said a solid state amp is preferred to power denon cans.  I'm looking into purchasing D2000 and have a Schiit Asgard amp with soon to be paired with a bifrost DAC.  Will the Asgard be a good match for these cans?

I have a set of D5000 that was paired with the Fiio E7/E9 DAC/Amp combo and I always thought they had bloated bass only on certain tracks.  I kept the Fiio E7 DAC with a Fiio L7 line out into a brand new Schiit Asgard and have noticed immediate improvements.  All of the bloat is gone while still keeping the incredible bass of the Denon AH-D*** line.  The Denon phones seem to be a great match for the Asgard.  As far as DAC's go, I'm getting an HRT Music Streamer II because I need a smaller DAC for my small desktop set up.

 

[WiR3D]

Quote:

I have a set of D5000 that was paired with the Fiio E7/E9 DAC/Amp combo and I always thought they had bloated bass only on certain tracks.  I kept the Fiio E7 DAC with a Fiio L7 line out into a brand new Schiit Asgard and have noticed immediate improvements.  All of the bloat is gone while still keeping the incredible bass of the Denon AH-D*** line.  The Denon phones seem to be a great match for the Asgard.  As far as DAC's go, I'm getting an HRT Music Streamer II because I need a smaller DAC for my small desktop set up.

To be expected, the E9 is very similar to the amp in my STX - and thats pretty much what can be expected.