[Bibo]

  your card seems to measure just fine and should already be mostly transparent if not totally so. trying to improve on transparent may not be audible be it on DAC or amp part. just check that you get enough power from your soundcard for the hd800 and that's about it.
what AlanU is explaining is more about coloring the sound than going for high fidelity. his system might very well measure worst than your soundcard because of that. not saying it's bad or wrong, just that he talks about getting closer to his taste, not closer to fidelity.

I think this may be the point. The headphone amp actually is a single chip (TI6120A2). It can put out 189mW max into 300 Ohms IIRC. The HD800 can take up to 500mW.
The DAC chip (TI Burr Brown PCM1792A) is used in high-end dacs >$1000 like the Antelope Zodiac or the Luxman DA200.
So maybe you should try a dedicated amp first with the stx as dac. You can always get a dac too if the amp alone does not do the trick. You would need the amp anyways if you go for an external dac.

 

[HotIce]

102db/Vrms @ 500mW is almost certain deafness.
500mW is the top power handling for the HD 800.

 

[Bibo]

I did not want to say that it does not get loud enough in general. But the HD800 have an impedance reaching from about 300 Ohms in the treble region up to more than 600 Ohms at 100Hz. An amp must be able to handle this. And a less powerful amp that is near its limits might not be able to reach the desired volume at 600 Ohms while it does at 300 Ohms at the same time. And what you get then is a HD800 with a harsh treble.
But I am just guessing, I neither own the STX nor the HD800s.

 

[castleofargh]

I did not want to say that it does not get loud enough in general. But the HD800 have an impedance reaching from about 300 Ohms in the treble region up to more than 600 Ohms at 100Hz. An amp must be able to handle this. And a less powerful amp that is near its limits might not be able to reach the desired volume at 600 Ohms while it does at 300 Ohms at the same time. And what you get then is a HD800 with a harsh treble.
But I am just guessing, I neither own the STX nor the HD800s.

it's late and I'm a little drunk, but I still feel like I should disagree with most of this.
I don't know how the soundcard behaves into 600ohm, but in theory, we go with 10ohm into 300ohm and then 10ohm into 600 at other frequencies. the difference in loudness won't be much with that damping ratio, and wouldn't more power be actually needed into the 300ohm part of the frequencies from more current?

 

[Bibo]

  it's late and I'm a little drunk, but I still feel like I should disagree with most of this.
I don't know how the soundcard behaves into 600ohm, but in theory, we go with 10ohm into 300ohm and then 10ohm into 600 at other frequencies. the difference in loudness won't be much with that damping ratio, and wouldn't more power be actually needed into the 300ohm part of the frequencies from more current?

As I said I am just guessing and I am no expert by any means. Actually I learned the technics behind headphone audio from people like you here on head-fi. So what I say now also might be BS...
But if you where right in this case wouldn't it  be easier then to drive headphones the higher their impedance is???
I do not know if Ohm's law applies here but if it does than you get half the current if you double the resistance and keep the voltage constant. And you need double the voltage to get the same current.

 

[dazzerfong]

  As I said I am just guessing and I am no expert by any means. Actually I learned the technics behind headphone audio from people like you here on head-fi. So what I say now also might be BS...
But if you where right in this case wouldn't it  be easier then to drive headphones the higher their impedance is???
I do not know if Ohm's law applies here but if it does than you get half the current if you double the resistance and keep the voltage constant. And you need double the voltage to get the same current.

Impedance governs voltage division only. Basically, when you deliver power to headphones, you need sufficient current and voltage to drive headphones. Hence the sensitivity measurement: x dB/mW, with mW being a function of voltage multiplied by current. Once you pass the impedance part, all the headphone cares about is the power.

 

[WilliamLeonhart]

Sold my DIY O2+ODAC (made from boards from JDS) the other day, since it was, well, ugly. Today I went to buy the "EHP-O2Di" from Epiphany, which is practically the O2+ODAC rev B, thinking (and secretly hoping) it would sound as good as my old one.
 
I was in for a surprise.
 
My PS500 (with Grado G cushs) always sound a bit too bassy, its mids a bit too recessed for my liking. In face, since the PS500 was not designed with G cushs in mind, sometimes it makes the singer sounds like they're covering a bit of their noses. With the new Epiphany O2+ODAC, these flaws almost completely disappreared. On most songs, the vocals sound very natural. The bass has become very clean and punchy. 
 
I have not spent much time with my new O2+ODAC, but I can say that it is a huge improvement from my old one. 30 or 40%, perhaps. It could be the build quality, or it could be the new ODAC. Anyway I'm very happy now.

 

[JacobLee89]

  Sold my DIY O2+ODAC (made from boards from JDS) the other day, since it was, well, ugly. Today I went to buy the "EHP-O2Di" from Epiphany, which is practically the O2+ODAC rev B, thinking (and secretly hoping) it would sound as good as my old one.
 
I was in for a surprise.
 
My PS500 (with Grado G cushs) always sound a bit too bassy, its mids a bit too recessed for my liking. In face, since the PS500 was not designed with G cushs in mind, sometimes it makes the singer sounds like they're covering a bit of their noses. With the new Epiphany O2+ODAC, these flaws almost completely disappreared. On most songs, the vocals sound very natural. The bass has become very clean and punchy. 
 
I have not spent much time with my new O2+ODAC, but I can say that it is a huge improvement from my old one. 30 or 40%, perhaps. It could be the build quality, or it could be the new ODAC. Anyway I'm very happy now.

 
Almost sounds like you had USB issues, considering that the ODAC Rev.b is designed to improve upon it's USB interface moreso than the choice of DAC chip.

 

[KeithEmo]

   
Almost sounds like you had USB issues, considering that the ODAC Rev.b is designed to improve upon it's USB interface moreso than the choice of DAC chip.

 
A difference in sound could definitely be USB-related. The original 0DAC DIDN'T have an async USB input; presumably the logic was that, since the Sabre DAC chip they used had internal jitter reduction, it wasn't necessary to tightly control jitter at the USB input itself. NwAvGuy mentions in his original description of the original 0DAC that he thinks async USB is unnecessary, even though "with adaptive USB the jitter will depend on the PC or other source". (With an async USB input, the DAC clocks the data from the computer, and so the jitter present on the input depends solely on how good a job the DAC does, and should be immune to things like differences in cables and USB ports. With an adaptive USB input, the jitter at the input depends on various things - including the jitter at the PC itself, and even the quality of the USB cable itself - all of which CAN affect the audio quality.)  
 
However, the new RevB version of the 0DAC no longer uses the Sabre DAC, so presumably it is now necessary to do a better job of avoiding jitter at the input (I don't think the new TI DAC they use has jitter reduction internally like the Sabre). I don't know if the new version is still adaptive USB, or if they've moved up to async - since they don't seem to mention it either way on the spec sheet.

 

[WilliamLeonhart]

I don't know much on technical details, so I just suppose any problems with my old ODAC (which was minimum, actually) only came from the lousy DIY build quality. In fact throughout my time with that one, I never had jitter or noises from the DAC. 

 

[Thenewguy007]

Can someone help?
I'm getting so many different suggestions & reviews that I can't seem to get a straight answer.
 

Looking for a amp, maily for my Sennheiser HD600 (also for Fidelio X1 & a AD700).
Is the O2 powerful enough to drive it?
Is the O2 a step down from the Asgard 2 amp or equal to it?
 
People have told me yes & no to both questions.

They also mentioned the Aune T1 mk2 & Little Dot Mk3 will blow away the O2 for amp use.
Would that be a fair assessment?

 

[headwhacker]

  Can someone help?
I'm getting so many different suggestions & reviews that I can't seem to get a straight answer.
 

Looking for a amp, maily for my Sennheiser HD600 (also for Fidelio X1 & a AD700).
Is the O2 powerful enough to drive it?
Is the O2 a step down from the Asgard 2 amp or equal to it?
 
People have told me yes & no to both questions.
 
They also mentioned the Aune T1 mk2 & Little Dot Mk3 will blow away the O2 for amp use.
Would that be a fair assessment?

 
It's confusing isn't it? That's the problem with this hobby. People have different "OPINION" about the same things. There are usually 2 camps/school of thought with regards to selecting an amp to drive a particular headphone.
 
1. Subjective/play it by ear - compare 2 amps by listening with each using your choice of headphone. People judge which amp is more powerful by the position of the volume knob. Then there's the individual's personal perception (e.g. tigher/bigger bass). Then select the amp which pairs/sounds better based on that perceptions.
 
2. Objective/measurements - Look at the specs (provided the specs published are accurate) or take basic measurements ( like voltage ouput, current etc) and calcluate the SPL in dB (how loud the amp can drive the headphone without distortion). Now, this is a bit tricky different people have different perception on how loud is loud enough. But the generally accepted max level is 120dB (threshhold of pain). Anything louder than that is considered bad. At this level our ears should only be exposed very briefly.
 
Now, if option 2 makes sense to you then O2 is powerful enough for all the cans mentioned above. However, if you believe option 1 is the way to go then there is no other way than to go out and try it yourself first before you make any purchase. Subjective opinions are very personal and what you hear does not necessarily means the same thing to me.
 
Sorry if this makes you more confused. 

 

[Bibo]

  They also mentioned the Aune T1 mk2 & Little Dot Mk3 will blow away the O2 for amp use.
Would that be a fair assessment?

This may only be true for use with the Sennheisers. The Fidelio X1s will need an amp with a low output impedance as they easily become uncontrolled and boomy in the lower frequencies if the output impedance of the amp is too high (See: Impedance mismatch, low damping factor).
The mentioned amps are both tube amps with higher output impedance.
 
The 02 works very well for me with the X1s and it is by far powerful enough, even at 1x gain.

 

[Thenewguy007]

Do the O2 have enough power to drive the HD600 or would they still be lacking compared to amps at the same price range?
I heard people say the Magi2 have more power thus drive the HD600 better.

 

[upstateguy]

  Can someone help?
I'm getting so many different suggestions & reviews that I can't seem to get a straight answer.
 

Looking for a amp, maily for my Sennheiser HD600 (also for Fidelio X1 & a AD700).
Is the O2 powerful enough to drive it?
Is the O2 a step down from the Asgard 2 amp or equal to it?
 
People have told me yes & no to both questions.
 
They also mentioned the Aune T1 mk2 & Little Dot Mk3 will blow away the O2 for amp use.
Would that be a fair assessment?

 
 

  Do the O2 have enough power to drive the HD600 or would they still be lacking compared to amps at the same price range?
I heard people say the Magi2 have more power thus drive the HD600 better.

 
the O2 is cheap and transparent.  It has more than enough power to drive 701s, 600s, 650s, 880s and T-1s.  just get one and start from there.