[NA Blur]

I think you are all onto two points:
 
1.)  The source you are using is extremely important in order to answer this question
 
2.)  Without empirical data, which can be obtained, the responses we are all going to have will be experiential and thus not support a solid conclusion.
 
Point 1

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If you are listening to a really bad source; say a really overly compressed mp3.  Now when you run this from your PC through an amp and then into a pair of headphones.  You just introduced 3 variables.  a)  The DAC converting your overly compressed mp3 to an analog signal your headphones can use.  b)  The amp and how it treats that signal and ultimately impedance.  c)  The headphone you are using
 
So to answer the questions best you need to be specific.  What type of source are you using?  How compressed is the audio already?  What DAC if any are you using or just the DAC inside an iPod or your PC?  What amp do you then want to run the signal from the DAC into?  What headphones do you want to test?  Without the answers to these questions you will receive a million opinions and never the real answer.
 
Point 2

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If someone out there has multiple DAC's and Amps laying around and the ability to measure the output in terms of frequency response please post the following measurements.
 
Experiment
Keeping the headphones, the music file, and source the same run the signal into a DAC and then into an amp and then into your headphones.  Keeping the headphones and DAC as controls take measurements through different amps.  Post the various signals.  Then keeping the Amp and headphones as the control test various DAC's and post those signals.  The results will be from the set of tested equipment which made the biggest difference.  As to the conclusion for all DAC's and all amps the data can only set a trend or at best a correlation.
 
I think for your question and presumably setup find the weakest link.  What component do you know you have that could really use some upgrading?  I know most people say that your source is the biggest thing to upgrade first then headphones.  You will notice the biggest audible differences with these two upgrades.

 

[Uncle Erik]

Quote:

The same thing could be said about amplifiers.  Many of the inexpensive DACs under $200 have a very decent built in headphone amplifier.  uDAC2, Xonar STX, Dr. DAC Nano just to name a few.  I'm just saying if I had $x00 to spend, I'd be much more inclined to spend more on my DAC.  I'd rather have an exceptional source with a straight pipe amp than a budget (but good) source and a fancy amp.
 
Would you really consider using a Burson HA-160 out of a uDAC2's line out?  I'd much rather have a higher end DAC with a simpler amplifier.
 

Amps have demonstrable differences. Look at output impedance curves - those cause measurable differences with different headphones, depending on the headphones' impedance curves. You'll also hear differences in topology, such as how much NFB is used, if any. There are many, many more variables.

The biggest variable with DACs is output power. It varies. Level-match and they're very difficult to tell apart.

And, yes, I have experimented with inexpensive sources. Fed into a good amp and speakers (probably about $12k of equipment (retail), if you enjoy judging quality by price tags) my old iPod sounds awfully good.

You might want to read up about the stunt Wilson Audio pulled at an audio show. The audience thought they were listening to some five-figure source when they revealed it was actually being fed by an iPod.

Great digital sources are dead cheap today. This is a good thing. Yeah, some status symbols might find the Emperor's New Clothes, but you can save quite a few bucks and enjoy great music. Isn't that the point?

 

[b0wl1ng]

Quote:

Amps have demonstrable differences. Look at output impedance curves - those cause measurable differences with different headphones, depending on the headphones' impedance curves. You'll also hear differences in topology, such as how much NFB is used, if any. There are many, many more variables.

The biggest variable with DACs is output power. It varies. Level-match and they're very difficult to tell apart.

And, yes, I have experimented with inexpensive sources. Fed into a good amp and speakers (probably about $12k of equipment (retail), if you enjoy judging quality by price tags) my old iPod sounds awfully good.

You might want to read up about the stunt Wilson Audio pulled at an audio show. The audience thought they were listening to some five-figure source when they revealed it was actually being fed by an iPod.

Great digital sources are dead cheap today. This is a good thing. Yeah, some status symbols might find the Emperor's New Clothes, but you can save quite a few bucks and enjoy great music. Isn't that the point?

Well said.
 

 

[milosz]

I would say that at a certain level, the DAC is more important.  What I mean by this is, at the lowest price levels, you may hear more differences in $50 DACs than in $50 amplifiers.  (I am just picking $50 here, to indicate LOW COST.  I don't know if there even ARE $50 DAC.)
 
I think you'll hear more variation in  cheap DACs than you will in cheap amplifiers. Careful choice of a cheap DAC could give you something that was OK, whereas I'm sure there are some crummy-sounding cheap DACs out there that you could end up with if you weren't careful. 
 
Once you get up past the $250 price range, both DACs and amps start to sound more similar than different. There are some differences but they get quite minor.  As you move up the price range, quality of all products on offer improves.  However, it would be wrong to assume that there's a direct positive correlation between price and quality.  A $10,000 DAC is not 10 times better than a $1,000 DAC.  It MAY be better, but maybe not; the only thing for SURE you can say about a $10,000 DAC is that there's more profit  margin to be had for those that sell them.  And it probably has a thicker face plate.

 

[n-phect]

A thicker face plate lol

 

[Willakan]

 
Quote:

Quote:

The same thing could be said about amplifiers.  Many of the inexpensive DACs under $200 have a very decent built in headphone amplifier.  uDAC2, Xonar STX, Dr. DAC Nano just to name a few.  I'm just saying if I had $x00 to spend, I'd be much more inclined to spend more on my DAC.  I'd rather have an exceptional source with a straight pipe amp than a budget (but good) source and a fancy amp.

The uDAC2 has serious channel balance problems, clipping problems and a high output impedance (which means frequency response into very reactive low impedance loads is affected). The STX merely has the latter. Having said that, it probably qualifies for pretty decent, but only if you're driving high impedance loads with it. 
 

 

[Anaxilus]

The most important is wherever your bottleneck is.   

 

[Ceja-Blu]

Power, only power will bring forth the true meaning of your sources.  uncle Eric is always 
spot on.  Listen to the voice of experience and reason.