[headwhacker]

 
I do agree with your rationale about the O2. I employed the same logic when choosing headphones and that led me to what are probably going to be my end-game cans, the HD 650 from Sennheiser. Using the Senn's has now allowed me to identify my end-game amp, the Project Ember.
 

 
It does not quite make sense to me. If O2 helped you find HD650 as your end game phone, then it should be mutually inclusive. O2 should be the same as well. Now that you realize that HD650 -> project ember is you end of game combo. Doesn't it tell you that HD650 isn't quite the headphone you thought it should sound paired with O2? 

 

[Solrighal]

What do you mean you're "not really sure there's anything wrong with the O2"? You mean ODAC?

Haven't heard the ODAC, but if anything, it's just limited by the filter. For those who like that filter, I think there could be none better than the ODAC.

 
You're absolutely correct, my mistake. I meant to say ODAC. It was late & I wasn't thinking straight.

 

[Solrighal]

   
It does not quite make sense to me. If O2 helped you find HD650 as your end game phone, then it should be mutually inclusive. O2 should be the same as well. Now that you realize that HD650 -> project ember is you end of game combo. Doesn't it tell you that HD650 isn't quite the headphone you thought it should sound paired with O2? 

 
I see what you mean & I agree, mostly. Being transparent, the O2 allowed me to hear into the sound signatures of various headphones. Of all the ones I bought the 650's were a revelation. I like their non-aggressive nature which, although perhaps laid-back compared to some, still reveal all the detail in the recording. I had no intention of upgrading the O2 - in fact I considered the O2 to be the ultimate amp. I started talking with some people on another forum and was persuaded to give the Project Ember a try. I was going to get it at home for a few weeks and - in my opinion - get the chance to finally prove to myself that valves were just hot air.
 
I was so wrong! The combination of the Project Ember with the HD 650 is magical. It's not expectation bias because I fully expected (wanted) the O2 to be superior. The Ember beats it in every way. All the detail is there but now there's a much larger sound-stage and a 'weight' to the music that was previously missing. I had to make a serious re-evaluation of my attitude to hi-fi. I was also lucky enough to have a Project Polaris side-by-side with the Ember & the O2 for evaluation. I liked it too but not to the same extent as the Ember. The O2 is undoubtedly transparent & for that it has to be commended. However, perhaps one of the more telling details in the O2's mission statement is that it has to be built for under $100. I feel that's often left out of discussions surrounding it. Are more expensive components better sounding? I have no idea. All I can say is that to my ears the Project Ember delivers a better sound than the O2.
 
So I'm buying a Project Ember. In an ideal world I would hold on to the O2 and do a similar test with DAC's but no-one's offering me a DAC at home to test over a prolonged period. I've already sold my O2 to part-fund my purchase of the Ember. Once I get my Project Ember I'll have the best sound I've ever heard via headphones. If I never get the chance to hear a different DAC I'll still be happy. But the O2 being beaten was nothing short of a revelation for me and so I can't help wondering if similar gains are to be had by a change of DAC.
 
None of this is to say the O2 is bad. It's absolutely not. If it's the only amp you ever hear then it's fantastic and maybe for some will always be the end-game. Not to me though. I can only go on what I hear. I didn't do any proper ABX testing or anything like that. I frankly don't believe I'm able to retain an accurate impression of sound characteristics when switching amps & I don't have any friends living locally who would be able to help me out anyway. I have to go on what my brain tells me after 6 weeks of auditioning. I'll tell you this - when I sent the Ember on to it's next tester I was bereft. To the point where I haven't listened to my headphones since.
 
Now I'm slowly amassing the money to purchase the Ember and when I have it I'll then look into a replacement DAC. If I get to test one and hear no difference then I'll be keeping my O2, saving some money & I'll still be happy.
 
I want to say this too. In no way am I trying to suggest that the Project Ember is the ultimate amplifier. There is a huge range of options out there & I'm almost certain there will be some that are even better. However the Ember really turned my opinions of amplifiers upside-down and, coupled with the warm feeling I get from the Ember community at DIYAH (without whom I'd have never had the opportunity to hear it) I'm happy that I've made the correct choice.
 
I hope that goes some way to explaining my reasoning & the decisions I've made.
 
Gordon.

 

[JacobLee89]

On a slightly differing topic. It seems like some of us O2'ers are slowly migrating to either Project Ember, or Project Polaris. One reason why I am on the reluctant side of making the move of buying one is due to the fact that my O2 has already gone through some mods, which - at least for me - has made some noticeable improvements. I'm unsure if the Polaris would offer much in terms of improvement. The ember is definitely a choice, but I don't feel comfortable with transporting tubes when I myself would be moving places quite often.
 
Actually, for now I think I will settle with this little bias of mine, just so that I can control my spending for a little longer..
 
*Edit*
Also I've seen the Bravo Audio S1 laying around in the void.. Some people say that - with some opamp rolling - they prefer it over the schiit magni. Unfortunately this amp hasn't seen much of the limelight over here, so that's yet another curiosity on my list.

 

[castleofargh]

are people moving to something else because it's an upgrade? or simply because they realized a little late that  transparent wasn't their idea of good sound?
IMO most people just want the sound of speakers in their headphones. that's what they call "real/good" sound. speakers tend to have some massive mess going on, be it from distortion levels or the impact of the room(plus of course the bass felt by the body). my own experience of tube stuff sometimes can give some kind of similar feelings and I really understand that many people would prefer that to transparent sound.
to me that's like adding lens flare on 3D rendering. you try to give a feeling of reality by adding the stuff we strive to get rid of IRL. and when we do get rid of those stuff, people call that unnatural ^_^.
 
for vinyl fans, lot of distortion, bad crosstalk, very rolled off trebles, and you turned that "nasty/cold" perfectly fine CD into the nice nostalgic sound of vinyls. colored amps are doing that in a special way. I do enjoy colored sound, but I would be very sad if I didn't also have the odac/o2 or another transparent amp as a reference.

 

[headwhacker]

  are people moving to something else because it's an upgrade? or simply because they realized a little late that  transparent wasn't their idea of good sound?
IMO most people just want the sound of speakers in their headphones. that's what they call "real/good" sound. speakers tend to have some massive mess going on, be it from distortion levels or the impact of the room(plus of course the bass felt by the body). my own experience of tube stuff sometimes can give some kind of similar feelings and I really understand that many people would prefer that to transparent sound.
to me that's like adding lens flare on 3D rendering. you try to give a feeling of reality by adding the stuff we strive to get rid of IRL. and when we do get rid of those stuff, people call that unnatural ^_^.
 
for vinyl fans, lot of distortion, bad crosstalk, very rolled off trebles, and you turned that "nasty/cold" perfectly fine CD into the nice nostalgic sound of vinyls. colored amps are doing that in a special way. I do enjoy colored sound, but I would be very sad if I didn't also have the odac/o2 or another transparent amp as a reference.

 
It's our nature to get sick of having the same thing repeatedly for a long time then when we experience something new we get a very pleasant feeling which will last as long as you get sick of it as well.
 
That is what I observe with myself and others in this hobby. Experiencing color or different flavor to the sound is nice once in a while, but I do it by changing headphones and/or eq. The changes are not too hard to detect and imo is easier to predict the than rolling amplifiers to get the desired coloration.

 

[diamondears]

It's our nature to get sick of having the same thing repeatedly for a long time then when we experience something new we get a very pleasant feeling which will last as long as you get sick of it as well.

That is what I observe with myself and others in this hobby. Experiencing color or different flavor to the sound is nice once in a while, but I do it by changing headphones and/or eq. The changes are not too hard to detect and imo is easier to predict the than rolling amplifiers to get the desired coloration.

Yeah, more options gets us farther from boredom aka upgradetitis. I have avoided upgradetitis on my gears by buying new HPs and playing around with 7 filters on my DAC. It's like having 7 CD players right in front of me. The O2 is perfect for this as its so transparent it just gets the signal from the DAC, passes it thru, and enable it to get accessed by the headphone thru the headphone jack out. In other words, with the O2, you can now see the music 20/20 from the DAC.

I really couldn't find any justification for buying another amp. I tried, looked for other amps regardless of price. Even when abroad I looked and looked. Couldn't find any.

 

[Solrighal]

  are people moving to something else because it's an upgrade? or simply because they realized a little late that  transparent wasn't their idea of good sound?
IMO most people just want the sound of speakers in their headphones. that's what they call "real/good" sound. speakers tend to have some massive mess going on, be it from distortion levels or the impact of the room(plus of course the bass felt by the body). my own experience of tube stuff sometimes can give some kind of similar feelings and I really understand that many people would prefer that to transparent sound.
to me that's like adding lens flare on 3D rendering. you try to give a feeling of reality by adding the stuff we strive to get rid of IRL. and when we do get rid of those stuff, people call that unnatural ^_^.
 
for vinyl fans, lot of distortion, bad crosstalk, very rolled off trebles, and you turned that "nasty/cold" perfectly fine CD into the nice nostalgic sound of vinyls. colored amps are doing that in a special way. I do enjoy colored sound, but I would be very sad if I didn't also have the odac/o2 or another transparent amp as a reference.

 
This is more or less how I interpret my experience too. I wouldn't necessarily say the valve sound is better but to me it's preferable. I deally I would have held on to the O2 but I needed to raise the money for the Project Ember somehow & selling the O2 is a step in that direction. I can't say I'm happy about it though.

 

[Medaud]

The only problem I have with my O2/ODAC is the channel imbalance at low volumes. I would upgrade if there was another Amp/DAC with the same transparency but without the imbalance.

 

[Solrighal]

The only problem I have with my O2/ODAC is the channel imbalance at low volumes. I would upgrade if there was another Amp/DAC with the same transparency but without the imbalance.

 
Could this possibly be because your gains are too high for the headphones you are using?

 

[JacobLee89]

The only problem I have with my O2/ODAC is the channel imbalance at low volumes. I would upgrade if there was another Amp/DAC with the same transparency but without the imbalance.

 
Odd. This would be the first time I've heard of an O2 with a channel imbalance.

 

[castleofargh]

 

The only problem I have with my O2/ODAC is the channel imbalance at low volumes. I would upgrade if there was another Amp/DAC with the same transparency but without the imbalance.

 
Odd. This would be the first time I've heard of an O2 with a channel imbalance.

the knob at low volume levels will tend to have some channel imbalance and you can have more or less luck depending on the knob. the very traditional advice is to avoid the first 1/4 or 1/3 of this kind of knobs. step volume and digitally controlled volumes are usually free of that problem.
@Medaud if you're not already at unity gain, look for how to get it(will need to get rid of a pair of resistors). if you're already at unity gain and it's still necessary for you to lower the volume into channel imbalance, then you can lower your computer by... IDK 15 or 20DB without any problem for sound(just select the output to be 24bit in your audio player). that often takes you out of imbalance.
else, you may want to look for an amp with step volume(each step is a pair of resistors so the imbalance can only be the error margin of the 2 resistors), the trouble with that is that you can't set the loudness in between 2 steps :'(. or else get something with a digitally controlled volume(pretty much the same idea but with a lot more values to set your loudness and maybe a little more noise). as portable amp I use the UHA760 for that very reason with very sensitive IEMs. but it's not a powerful amp like the O2, so it should be limited to portable gears.

 

[Medaud]

Could this possibly be because your gains are too high for the headphones you are using?

I'm on 1x unity gain, headphones are ATH-A900x with windows volume slider at 98% and default format in windows set to 24bit 96kHz.

Odd. This would be the first time I've heard of an O2 with a channel imbalance.

It's been mentioned quite a few times. Only happens when you turn the volume knob way down.

the knob at low volume levels will tend to have some channel imbalance and you can have more or less luck depending on the knob. the very traditional advice is to avoid the first 1/4 or 1/3 of this kind of knobs. step volume and digitally controlled volumes are usually free of that problem.
@Medaud
if you're not already at unity gain, look for how to get it(will need to get rid of a pair of resistors). if you're already at unity gain and it's still necessary for you to lower the volume into channel imbalance, then you can lower your computer by... IDK 15 or 20DB without any problem for sound(just select the output to be 24bit in your audio player). that often takes you out of imbalance.
else, you may want to look for an amp with step volume(each step is a pair of resistors so the imbalance can only be the error margin of the 2 resistors), the trouble with that is that you can't set the loudness in between 2 steps :'(. or else get something with a digitally controlled volume(pretty much the same idea but with a lot more values to set your loudness and maybe a little more noise). as portable amp I use the UHA760 for that very reason with very sensitive IEMs. but it's not a powerful amp like the O2, so it should be limited to portable gears.

Would it work to just lower the windows volume slider further? How would this affect the quality of sound, would there be any audible difference? Thanks for the advice.

 

[castleofargh]

well you go with the idea that 1bit gives you about 6db, so the problem is to know how many effective bits your DAC has.
by lowering the volume on the computer you can visualize it as cutting the quietest part of the signal. you really have no need to go all the way down to 24bit for the music signal as albums will usually not go past 65 or 70db of dynamic even for classical. so the question is how low you really need the quantization noise to be?
 
you can turn the windows value to decibel instead of percentage, that gives a better idea of what you're doing I think(just right click the value into sound properties and it will let you select % or db). I just set the volume in foobar, but I can understand how it's more convenient to set it in windows for utube games etc.
 
in my situation, I tried to get the lower value on the O2 that had no big obvious channel imbalance(checked with some tones looped into my soudcard) and from that I went to set my computer. I never had to go below -15DB in foobar. to that you add the replaygain I use on all my tracks so the value changes depending on how dynamic the song is, but let's say around -10db/-15db for not dynamic songs. so I end up at about -25db/-30db when I listen quietly to metallica... and above for my usual listening levels and for anything with some actual dynamic in the song.
6*5=30db so I give away 5 bits max, not really a drama for me, but for somebody with a 16bit DAC it's another story.

 

[adydula]

There's a new build of the ODA over at DIYAUDIO if anyone is interested:
 
http://www.diyaudio.com/forums/headphone-systems/229934-version-o2-desktop-amp-oda-74.html
 
You can follow this persons build to see if you think you might want to tackle the project!
 
Alex