The sound quality from DACs - is it all the same?

So it seems this thread is coming to the conclusion that better sounding DACs don't meet any objective engineering requirements better than cheaper dacs. It's not that they produce the signal more precisely, but that they add some special sauce that creates a more pleasant stereo listening experience for some listeners who find the experience worth the extra cost. 

What I want to know is if the left channel of my dac sounds the same as the right channel? Do two copies of the same design always sound the same? If your hearing is acute enough to be bothered by differences between samples of the same design you're going to have a really rough time, or a really fun time if you like buying 10 copies of the same  dac and listening for the best one. It may be that cheap dacs with more variation between units have the possibility of striking up magic from time to time. If you've got the ears, money and time, then go hunt for the magical sounding  cheap dac! If there's a real science to separating good sounding dacs from bad ones, that would be interesting to know. So far I haven't heard of any good explanations for why expensive dacs should sound better, other than by adding distortion that some people like. 

If I think I hear something different, my inquiring mind wants to know more about what is going on. I know some just want the result and don't care to know the technical differences about the soundwave that is actually reaching their ear, but I want to know. If a dac creates a different sound then that means it causes the driver in the speaker to move differently than another dac, which means the pressure variations that my ear detects in the air are also different. I'm hard pressed to believe that differences in the sound reaching my ear that I can detect are not measurable with a good calibrated microphone and some software. Nearfield testing of a small speaker should easily do the trick. If the dacs are changing things then we can measure minute differences in level at any frequency, as well as phase, timing, distortion, and noise. Any ringing, reverberance, decay. Certainly it would show up and we could more clearly define what is creating the "good" sound. Is it increased accuracy or some kind of euphoric distortion? If it's a departure from linearity then we are off into a confusing world where people who are making albums are hearing something different than those playing it back, and components are all adding an array of colorations to each other to create effects that may appeal to some and not to others. I'd rather we all get as close as possible to a standard so we can hear what the content creators had in mind for us. I don't want my system to sound good. I want it to not have it's own sound so the creative content can be delivered to me as intended. I want the content to sound like it should, and my system to sound like nothing. Or if it does sound like something, it should be the same something the content creators had in mind. I'm not doubting that there might be some real differences, and that something is indeed getting better as dacs go up in price. But I'd like to see exactly what it is, not just an explanation of how well the circuits are implemented and how good the clocks are, etc. Exactly what about the sound that is reaching my ear has changed?

I really wish all SQ elements are measurable such that, like I mentioned in other topics, a matrix can be established as a basis to more objectively assess the performance of speakers and other gears. But, so far, other than decay, SPL and related vertical/lateral responses, distortion/noise such as SNR or SINAD, etc., what other sound traits have been scientifically measured/reported? The dynamic range can possibly be done easily but was never reported at least to my knowledge. Can the width, depth and height of soundstage be measured accurately in spite we know the SS is created/affected by the delay of sound arriving at ears? How can one measure imaging, separation of intruments, the quality of bass such as speed and weight of bass, etc.?

Dynamics are a point of interest for myself, as I think I’m hearing a dynamic difference if I digitally attenuate the signal before I send it to the DAC, and then turn up the pre-amp volume. Technically you’d expect a loss of dynamic range by doing this, but my perception is the opposite. I guess I should try to come up with a way to measure this. My DAC chips are missing their output stages so there could be some self limiting compression going on with a full strength signal. As far as sound stage width, depth, and height are concerned, my experience is that room reflections, speaker placement, speaker dispersion, and equalization have dramatic effects on these. The known factors in the recording are timing and level between the two channels. If both are playing the exact same thing it should create a phantom image at center. There is no depth cue that can come into the recording other than echoes and equalization and relative level. Our ears don’t directly calculate a sound source distance in the same way that our eyes can do it by vector calculation of how crossed our eyes are, or how large an object of known dimension is appearing on our retina. With the ears it’s just timing and level, for direction left to right, reflections and equalization for height, depth, and determining if a sound is in front of us or behind us, along with comparing how things change when we move our heads. I don’t doubt it could be quite helpful if both channels are immaculately matched in all areas of performance throughout the audio chain. Now that I've said all that, anybody please correct anything that you think is wrong. It occurs to me that any level compression effects could reduce the sense of depth by making quiet echoes and distant sources sound too loud.

@ghdprentice

Sounds great according to them. You would wonder how they assess what sounds great. If it’s done by swapping components and then blind testing that would be most interesting. Then of course I’d re-test to see exactly what changed because it may be possible to achieve the same result in a more cost effective fashion. This would also add to a body of knowledge about which deviations from linearity sound great and which don’t. If the change passes a blind test but nothing measurably different can be found then that is also an extremely interesting finding that would expand science and engineering in ways that would extend past the field of hifi. I see little of that kind of contribution from the world of audio reproduction happening, so I’m convinced that the "secret sauce" has to be some audible deviation from linearity that offers nothing new to the general fields of science and engineering, and it seems unlikely that expensive sub components would be required to create the most pleasing effect unless one grooms one’s tastes in that direction. This gets me thinking of moissanite vs diamond. Moissanite actually exceeds diamond for fire. It diffracts light more strongly. This would seem desirable but since it is known that moissanite is cheaper than diamond the extra fire is seen by some as a tale tell of it’s cheapness, thus it is not as beautiful as the more restrained fire of diamond.

@ghdprentice

Companies that produce really high end equipment are not unaware or stumbling around. They don’t play with blind tests any more than the top birders in the world need to refer to google to make sure of the correct identification of a sparrow.

I totally agree. They know what they are doing, and huge part of that is marketing their story. They know better than to try to compete in a lower cost market even if they could make products with their house sound for a significantly lower price. It would be as futile as if Ferrari tried to try to compete in the sub $30k new family car market. They don’t know how to do it. It ain’t easy at all! They could possibly team up with Toyota, but that would just tarnish their brand image, even if it turned out to be an excellent family car. The people who buy Ferraris don’t want to see the label on every low end sedan and mini van everywhere. The people who don’t typically buy Ferraris aren’t going to care much about that label. Making a car analogy is somewhat weak because a fast Ferrari easily has measurably better performance than a sub $30k family sedan. With audio equipment the "performance" as it might be measured typically doesn't correlate much with the price. So it's paying for taste, just like paying for styling on a Ferrari compared to some cheaper car someone has hot rodded so it's crazy fast. High end exotic cars typically get their special looks by having small amounts of internal usable space compared to the size of the car. Any practical design cannot look the same.