I'm just curious....
You said "Every one of them sounded the same for the purposes of listening to music in the home"....
Does this mean that you actually did in fact conduct a bunch of proper, level matched, double blind tests between a bunch of them....
Or just that "you actually tested one or two and didn't notice what you considered to be obvious differences between the rest"?
I only ask because, to be quite honest, in many cases I find the differences to be small enough that I can ONLY notice them,
when listening specifically FOR differences, with certain content, and with certain speakers or headphones.
Therefore, I would agree that "for purposes of listening to music in the home" I wouldn't notice the differences either.
When you asked for "an obvious example" I mentioned the Wyred4Sound DAC2 and my DC-1 because I found the differences in sound between them to be quite obvious.
I had planned to sell the Wyred4Sound, and a friend of mine, who designs speakers for a living, had expressed an interest.
I had used the W4S as my main DAC for several months - and found it quite acceptable - before switching to a different one.
I had never compared it directly to another DAC before, but my friend, who already owned a DC-1, was curious if there would be an audible difference.
We tried comparing them, with three different pairs of very neutral speakers, and two different amplifiers...
And were quite surprised at how different they sounded.
(He remarked that the difference was actually greater that the difference between the various speakers.)
I did NOT run a frequency response sweep on the Wyred4Sound at the time.
However, at some point when I was using it, I did run one (I don't recall the details - but an error of even a fraction of a dB in frequency response would have been noticed as odd.)
SInce, as far as I know, W4S has a decent service record, I doubt that it had mysteriously drifted (that sort of error, the same in both channels, would be extremely unusual).
It has been my experience that DACs rarely suffer the sorts of failures that would cause errors in frequency response.
(Also, since they would be due to a failed analog component, the odds of the same flaw appearing in both channels would be very tiny.)
We've tested plenty of DC-1's, some with circuit problems, but I don't recall ever hearing one where everything else worked fine, but the frequency response was off.
(Most DACs sound different, when they do, because of deliberate or unintentional DESIGN differences.)
As for the cause being due to differences in the filters....
That is simply a pet theory of mine.
Knowing that the filters are different, and that, on DACs like the W4S, which offers several filter choices, the choices DO sound different, it seems like a reasonable hypothesis.
Also, offhand, I can't think of anything else that might account for it.
However, to be fair, I am NOT specifically convinced that it's the cause.
There could quite possibly be some OTHER factor that I haven't thought of.
For example, Sabre DACs include an internal mechanism that operates something like an ADSR, and is intended to reduce jitter.
It uses a sort of "intelligent oversampling" that "calculates corrections to compensate for jitter and inserts them in the data stream".
(Sabre has a cool name for it.... but it amounts to figuring out when there's jitter, and adjusting the upsampled data stream, to "compensate" for the errors.)
Therefore, since the data stream is altered, it is not unreasonable to suspect that it may produce some sort of audible effect.
Also, one of the previous Emotiva DAC models included an ADSR for jitter elimination that could be instantly switched on and off by a button.
An ADSR alters the sample rate, but in no way alters the amplitude or frequency response of the data itself.
The ADSR acts as a sample rate converter, but the resampled data is synchronized to a new clock, which eliminates jitter.
However, as with the mechanism in the Sabre DACs, the actual math used to calculate the corrections is very complex and quite proprietary.
(Analog Devices offers a "conceptual description", but the math is proprietary; all they claim is that "any errors it introduces are at least 130 dB down.)
Be that as it may, it is simple enough to switch the ADSR in and out by pressing a button, with no measurable effect on the S/N or the frequency response.
Yet, interestingly, MOST people agree that the ADSR changes the sound (usually seeming to cause slight changes in the sound stage).
(Although the asserted purpose is to reduce or eliminate jitter, the change seems audible on many sources, even those that seem unlikely to have jitter to remove.)
Now, in this case, it should be somewhat trivial to analyze the data stream, and confirm that "all the bits are new and different".
However, the basic measurements remain virtually the same, yet the "sound" changes slightly.
(I would suggest that neither is better, but, when switching quickly back and forth, a "change" is somewhat obvious.)
To me, as a generalization, all this strongly suggests that "there are things going on we haven't accurately quantified yet"...
(Of course, it could turn out that there really is a small difference in frequency response, and it is simply the claims about the limit of audibility on things like that are incorrect.)
I wonder whether, for example, you have actually done a double-blind test between an Oppo 93 and an Oppo 95...
(Oppo claims that the xx5 models sound rather different than the xx3 models because of their Sabre DAcs.)
Or whether you have simply CHOSEN to believe the results of a few outdated, and poorly executed, tests.
I will ask again....
Have you ever actually run or seen the results of a properly designed and operated test to determine whether Sabre DACs sound different than other DACs?
Or, for that matter, to determine whether various DAC filters are audibly different - EVEN IF THEY DELIVER ARBITRARILY LOW DISTORTION AND FLAT FREQUENCY RESPONSE.
Or are you INFERRING that to be the case, based on a little of your own personal anecdotal data, and the results of a bunch of vague and not totally relevent tests?
I have eight iPods from the raised wheel one through the last brushed aluminum classic. I have an Oppo HA-1 that includes the Sabre chip. I don't generally use my speaker system for comparison tests, because that introduces too many variables with distortion and room acoustics. Instead, I use Oppo PM-1s. I've compared a Pioneer blu-ray player, an Oppo BDP-103D, a Sony blu-ray player, a Philips 963SA DAD/SACD player, three different versions of the iPhone, 8 0r 10 different Macs- from the 8500AV to a recent iMac, and a cheapo DVD player from Walmart. Every one of them sounded the same for the purposes of listening to music in the home. That menagerie of gear runs the price range from $40 to 300 times that. It covers portable gear, home gear, A/V gear, phones and players capable of HD audio. I'm looking for something that sounds different. I haven't been able to find it yet. I've just given you a whole laundry list of things you can use to verify my claim that they all are audibly transparent. You probably own some of this stuff or gear just like it. Please! Go check me. I welcome your verification. If there is a difference I missed, I would like to pinpoint it myself, quantify it and find the reason it occurred so I don't make that mistake in the future.
I would be happy to entertain the idea of a DAC or player that sounds different. I would actually be pleased to find one. The problem is, whenever I ask someone in an audiophile group for an example that sounds clearly different, I get a verbal runaround as soon as I try to pin down the claims. Either they point to differences in specs that are clearly not audible, or they base their opinion on subjective impressions and sloppy testing procedures, or they do what you just did... tell me that I have to jump through a million hoops to verify the claim properly. When I call them on the runaround, the conversation usually degenerates to them pulling out the old saw "Either your equipment sucks or you're deaf."
I'm sorry, but I'm not deaf, and I'm not dumb. Just because someone claims in an internet forum that they did a controlled test and clearly heard a difference, that doesn't force me to accept the fact that in "one comparison, under one specific set of circumstances a difference was proven." At the beginning of this, I gave you the benefit of the doubt on that for the sake of argument in the hopes that you would produce a way to get verification. But that led nowhere.
I'm not claiming to try to prove a negative by saying different DACs don't exit. That's just a straw man. I'm just asking for one clear example that we can all verify. But you've worked very hard to make it as impossible as possible for anyone to verify your results... tthe model you used is out of production, you don't own it any more, your system is different than other people's, to capture it you need 10x the audio quality of what you're recording, we would have to sample 50 people and run the probabilities to know for sure, etc, etc... The only supporting arguments you've put forward are that lots of people say Sabre DACs sound different and a bunch of stuff about how filters might theoretically cause differences... but you haven't proven yet that a difference exists!
I don't want you to think I haven't been reading your posts. I was just politely ignoring the prevarication and slips in logic in the hopes that it would lead to a way for me to find a recent DAC or player that sounds different. That's what I do. I don't try to grab on to every little semantic argument, because I don't want to feed the circular arguments that go on here in Sound Science all the time. I just keep my eye on the prize. I skip past the rhetoric and I focus on the nugget of real stuff buried underneath. I patiently wait for the truth to reveal itself... at least until it seems pretty much guaranteed that it's never going to arrive.
A clear audible difference should be clearly audible. If you really did regularly hear clear differences between DACs, it would be easy for you to point to an example that would be relatively simple to verify and audible on any good system. I actually think you honestly believe DACs do sound different. But that belief is based on bias, not actual experience or comparison tests. You might not want to know the truth. That is very common among audiophiles.
