Thanks, fellas. (sorry, I forgot to respond earlier)
Around the web I've read many people saying exactly what Flint's said, and I trust it in general. I have assumed there's a great deal of placebo at work in the area of $1000+ DAC's. But what about something like a phone or laptop? I am quite sure I hear some extra life when I use any decent external USB DAC (like the $50-100 types), compared to using my phone's headphone out jack. Of course I realize there's also the effect of bypassing the phone's headphone amp (likely quite cheap) in this scenario.
Anyway, the real reason I decided to ask is this:
My main source is a 1st Gen FiiO X3, which has 3 output options: headphone, line-out, and coax digital. For years I have been very happy with the sound of the X3's line-out (Wolfson DAC) into the RCA aux input of my receiver. But it just occured to me to try the digital out and see how the Marantz's DAC compares. I swear I hear a little more energy in the high end going this route, albeit subtle. But it's also a bit louder so that may be all I'm hearing, I dunno. I also may be influenced by everything I've always read about the warm/smooth nature of the Wolfson DAC. Who knows.
Last point/question:
DAC quality aside, how about what people always say about the difference in character of all the premium DACs? Wolfson, warm; Sabre, clinical, Burr Brown, whatever; Cirrus, whatever, etc. Is that all kinda bunk now?
Really last point:
I don't care what anyone says about any of the above, some day soon I'm getting a Modi/Loki/Magni Schitt stack because I just wanna. And whether it's true or not, my HD600's will sound way better. Period.
Any device
CAN sound different from any other device. But the idea of "better" is rarely related to technical capability.
Remember that in every case of auditioning any component, a difference in listening level of as little as 0.5dB will be audible and almost always the louder component will be perceived as better. I even did a test in my recording studio back in the 1990s where I told people they were testing two amplifiers and all they were actually comparing was the same exact gear and I was merely switching a linear 0.8 dB pad in and out of the signal chain. Everyone who participated across the board perceived the louder signal to be better, most thought it was significantly better. Only one participant recognized that we were only comparing listening levels, but he was a trained listener.
So, you cannot make an honest "Apples to Apples" comparison of anything without ensuring the listening levels are exactly the same. I do it by using a voltmeter to measure the voltage at the speaker terminals while playing a 60Hz sine wave from the sources and adjusting until the voltages between the two items being tested are exactly the same - and I mean EXACTLY THE SAME.
Now, as for phones it is true that most phones use output circuits which can operate both as headphone amps and as line level amps without any work on your part to change the characteristics of the circuit. As such, while they can be incredibly good for what they are, I still believe a true line level output stage will outperform a mixed-mode output stage which can also drive headphones. In that case, a proper DAC would usually be an improvement. However, I deeply believe that a well made $50 DAC is every bit as good as a $1,000 audiophile DAC for the job of connecting a phone to a stereo system - assuming the only function of the unit is to convert the digital stream from the phone into a pure analog signal with no additional processing. In most cases, those costly high end DACs do many other things than merely convert digital to analog and those features might justify the added cost. Many also offer media streaming, Bluetooth connectivity, digital input switching, and some have outstanding headphone amps integrated into them. A cheap $50 DAC might not have all those things.
As for the claims about the "sound" of a model of chip being used in a DAC, I declare almost all of that total and complete BS. I would put money up that no one making those claims could prove that they hear any difference between any properly designed DAC using those different chipsets. Try to challenge them to do a proper double-blind ABX study where the levels are perfectly matched and I bet they wall all refuse to participate. Anyone who would dare to participate would be found to not hear any difference at all. I guarantee it.
As for different commercial DACs on the market, some do sound different than others. I've seen high end DAC with a flat response to the highest frequencies of the digital signal's capability and I've seen then with subtle reduction in the treble starting at about 10kHz and increasing to as much as 1.5dB as 20kHz. Between the reduction in treble AND the phase shift such an EQ would add, the sound you hear will be different from a DAC without such a filter. Many LP lovers find digital to be harsh because they are not accustomed to the flat, clear, undistorted high frequency range of digital audio. So, putting a slight roll off at the top end of a DAC can make the sound more pleasing to someone who really loves how LPs sound. That's fine for them. But it isn't accurate. Some of the Vacuum Tube DACs add way more harmonic distortion than any audio engineer would have ever wanted 40 years ago, but that "TUBE SOUND" many people love is in fact the added harmonic information. So, it is fine if one likes a highly distorted tube DAC, but it isn't accurate or a realistic representation of what's in the source data.
Finally, it is extremely important in this hobby to remember that our brains fill in all of the missing information our ears and eyes cannot perceive in order to know what we are listening to. It is also extremely important to remember that our ability to accurately recall what we hear (not what instruments or notes we heard), but the audio waveform which are eardrums, inner ears, and cochlea turn into electrical information our brain uses, our ability to remember audio is limited to just a few seconds. What we remember is our impressions of what we heard. If I listen to a pair of B&W speakers, I will remember how bright they were, how they made me feel, how difficult or easy it was to make out instruments, and so on. However, I will not remember the exact sound that came to my ear. So, it is flat out impossible to compare the actual sound of any two devices if you are not switching between them nearly instantaneously while judging them against each other. What you can do is remember your interpretation of what you heard, but that is influenced by your mood, what you were expecting to hear, how you felt about the device before you heard it, and so on.
If I spent a month telling you over and over and over and over that all DACs always sound exactly the same no matter what, and if you deeply believed that in your heart of hearts, you could be auditioning two completely different sounding DACs a few hours apart in different locations and at the end of the day you are more likely to believe they sounded exactly the same. In other words, we are VERY easily fooled by what we are told we will hear. If I am told over and over and over and over that Wolfson DAC chipsets always sound warm compared to other DAC chipsets, then every time I listened to a product which I knew had a Wolfson DAC chipset I would be pre-inclined to seek out evidence of the sound being warm. I would ignore evidence that it wasn't warm sounding. I would go to great lengths, completely unconsciously, to guarantee what I expected to hear is what I actually heard.
This ability to completely fool one's self gets greater as the differences in what we are hearing get harder to make out. If the difference between one cable and another cable was a reduction in resistance of 0.001%, yet I was convinced one cable would be more "organic" sounding than the other and I really did think all my friends and trusted reviewers were likely to be correct in their claims about the different "organic sounding" cable, then I will totally hear it that way when I audition the cable. This is why truly blind tests are necessary. Tests where you are not being told what you will hear before listening to it. Tests where everyone is blind as to which device is being auditioned.
So, take everything with a grain of salt, even my rants. Be rational, do what makes you the happiest, and try not to waste your money just because everyone else is.
Consider what matters most. Would you rather own a $1,000 DAC which may or may not be different from a $50 DAC, or would you rather have a $950 pair of headphones with a $50 DAC? Would you rather spend money on electronics that might sound different, or would you rather spend money on speakers that you know for a fact sound different?