Originally Posted by esldude
I know sighted listening of DACs sounds convincing. But like other things it just doesn't pan out.
You say you cannot find data leading to the conclusion there isn't a difference between DACs that is more stringent than guys listening to stuff. There is plenty.
Frequency response is 20hz-20khz for humans. Keep that flat and there is no room for that to matter. Generally distortion is inaudible below .1% and usually much higher with music. Signal to noise, instantaneous SNR for ears is maybe 60 db but just to be safe less ask for 80 db. But with the fact few rooms are quieter than 30 db noise levels adding 96 db on top of that puts you over the threshold of pain. None of this is unsupported data. It is all well established material. I am not going to cite each and every source for that, but if you doubt it such is easy to find. Or we can point to textbooks with the info for you to read. So, did I mention DACs in this paragraph yet? Nope I didn't. However, any musical delivery system, any blackbox that can take in a music signal digital or analog and put it out with accuracy equal to or better than the above envelope will sound audibly transparent. .01% THD will not sound audibly different than .00001%. So on and so forth.
So looking at the above guidelines how many DAC's fail to be flat in response, less than .1% in THD and IMD, with less than 80 db of SNR? I think you will find the answer is very few indeed. So for a DAC to sound different you need a signal different. When the differences lie at extremely low levels (and they do I have measured a few, so have many people) what is present in the signal to hear as better or worse? So no we don't go around performing an ABX test on every pair of DACs in existence. We don't need to do so. We have well supported data to the abilities of human hearing, and when something fits well within it the result won't be discernibly different. Those times when more rigorous testing has been done give results that line up with that knowledge. No need to re-invent the wheel in each case so to speak.
Now the other part of this is how we get fooled in hearing differences we can perceive as so real, but aren't there. In this there is much data, much research, not just in hearing, but in all of our senses showing how easily our brain generates non existent differences. Our brains could be described as pattern matching difference engines. Predisposed in a myriad of ways for finding a difference. There was great evolutionary and survival value in that built in bias. But at the margins of perception it generates differences which aren't real. Usually it is much safer to operate on possible differences that aren't real than it is to perhaps miss a difference which is real. Real missed differences could cost you your life. Just as obviously is the emotional, gut level, strength at which those perceptions will function. It had survival value for our kind. But in a modern context for which we have not biologically adapted it can lead you astray. Buying overly complex or expensive audio equipment isn't deadly for the most part.
Stuff in bold: Yup, that's pretty much normal.
Sutff underlined: That's very few. Different to none. Even "hifi" DACS. SilverEars just managed to post an FR that isn't flat to 20kHz.
Stuff in bold + italics: The magnitude of the difference really depends on the DAC. I'm sure if you listen to the Wadia or the 801 posted earlier, you'd notice a difference between them and other DACs. I'm pretty sure the difference between the HM-801 and the Clip+ will be audible.
I really think we're arguing over different things here. What you seem to be saying is that all modern Hi-fi DACs are the same. I am saying NOT ALL of them are the same. Most are very similar, but not ALL. I'm not talking about only obscure DACS from flea bay, but DACs you find on most audio forums and sites. That is all. I am not stating that there is, say a difference between a Mytek and a Benchmark or whatever. Simply that not ALL sound the same.
The information I mentioned I cannot find is that there is no information that states that ALL DACS sound the same.
Again, I refer you to the ODAC's development blog. One part of the very long blog mentions:
The ODAC has been through four lengthy revisions—two of the earlier boards are shown to the right. Despite the fact we started with essentially the reference design from the datasheets, the devil was in the details. The first version played music and sounded OK. Many companies and DIYers that “design by ear” would have stopped there. But that first version didn’t come close to delivering what the DAC chip is capable of. Each revision cycle took at least several weeks, cost hundreds of dollars, and involved countless hours of work. But, in the end, it resulted in muchbetter performance compared to where we started..
I'd like to focus on the "much better performance" part. The designer was someone who's never far away from the "what's audible" since the start and began with what was close to what you mentioned in terms of human hearing ability. So I am assuming that he's saying version 4 is audibly better than version 3, 2 or 1.
At the end he said that in a blind test he and one other could not tell the difference between ODAC rev.4 and the Benchmark 1. Which is great and follows what you're saying. But had they stuck to Rev.1, 2 or 3 for production it would not have been. Which is sort of my point - DACs can be designed poorly and the difference between a poorly designed DAC and a well designed one is audible. I don't know how good DAC's are in things like cheap CD players and so on, but the ODAC was designed using many very sophisticated equipment and the designer himself insisted that he would not be able to achieve this result without said equipment. Some people design "by ear" and some simply just don't have the test equipment or simply do not/cannot use them who knows. But it is possible to design a poor dec and even more possible to sell them.