Since publishing the results from the NUC measurements a week back, permit me to discuss the topic of "audiophile" music servers, streamers and transports - specifically addressing the idea some have that they make a significant sonic difference.
As audiophiles, we've all seen them reviewed in the various websites. Names like Aurender, Antipodes, SOtM, Small Green Computer, Baetis Audio for machines that run either Windows or Linux, or more customized non-PC looking devices like the Auralic streamers, SONORE microRendu (Wow! So much hype!), and established audio companies within the arena like PS Audio, Ayre, Bryston, Simaudio, etc. Even JRiver sells their customized NUC server/player, called the Id.
Although the hardware features may vary significantly (with potentially extra cost associated): Does it have an integrated CD/DVD ripper? What digital interface is available (USB, ethernet, S/PDIF)? Is there an integrated DAC?
And the software set-up may be quite different: Windows? Linux? MPD? JRiver? Squeezebox? Roon endpoint?
The fact remains that these devices are basically microcomputers at heart in typically small cases and ultimately operate in the digital domain to send data to the DAC for playback.
On Computer Transports and Sound QualityUnless programmed to manipulate the digital data, if we're talking about "bitperfect" transmission of digital audio to an outboard DAC, there is no reason to think there is any unusual or unique "sound" to these devices as demonstrated by the NUC vs. ODROID-C2 vs. laptop vs. HTPC measurements. Asynchronous interfaces (like USB and ethernet as previously examined) have already dealt with jitter for years such that nobody to this point has demonstrated audibility differences in controlled tests, and therefore in my opinion the only thing left is the issue of electrical noise which is the bugaboo being touted as the rationale for all kinds of digital audio "problems" these days.
In "dealing" with this "issue" of electrical noise, all kinds of tweaks have furthermore been offered for sale to prospective buyers (or at least those audiophiles with enough faith to accept the "diagnosis" and "cure"). Gear like the Audioquest Jitterbug, UpTone Audio Regen, iFi iPurifier, optical ethernet isolators have been suggested (like the TP-Link MC200CM), as well as the upcoming PS Audio LANRover (reminds me of my tests using the inexpensive USB ethernet extender) are all being touted as beneficial when hanging off your USB port!
After all these years of listening and testing encompassing laptops from Apple and those running Windows, to Microsoft Surface Pro, to a recent MacBook, to Linux OS, to low-power ARM machines like the ODROID-C2, to motherboards like the Gigabyte or ASUS, to software OS optimizations and "audiophile software music players" like Fidelizer and JPlay, and the Intel NUC recently, the conclusion is rather obvious to me. Bitperfect playback from a reasonable quality computer, using an asynchronous interface, and through a reputable DAC would result in the same sonic output irrespective of claims I've heard otherwise. I have found no need for special power supplies, fancy cables, or specialty devices for example to clean up the USB signal. In my mind "reasonable" just means a device that's known to be reliable and has a good reputation, rather than something that needs be endorsed by an audiophile guru. This is the most logical position to take intellectually given how digital devices work, based on objective results I've found, and subjectively I have no cause to testify otherwise. To put it bluntly... Yes, "bits are bits" using modern digital computer playback hooked up to a good asynchronous DAC!
This doesn't mean I don't have preferences for the soundroom playback device of course. Some devices might operate faster. I might prefer a certain tablet control app. Acoustically silent fanless devices are great. I might like a certain appearance or size (sure, heavy devices created out of beautifully machined metal can look great and instill confidence). I might want a multitude of digital in/out options. I might prefer DLNA +/- Roon +/- Squeezebox playback. I might want the ability to hook up a local USB drive. These are just some of the potential features and subjective values I might place on the device and if important, I wouldn't mind spending extra money on these qualities. However these features generally would not affect the ultimate utilitarian function - "high fidelity" audio playback.
Time and again, tests show that a good DAC like the TEAC UD-501, or Light Harmonic Geek Out V2 can resolved >16-bits of dynamic range (>96dB), with no evidence of added distortion, nor change to frequency response with any of these computers serving the data. This means that in a properly functioning system, you really can't say that one bitperfect device "brought out the midrange", "controlled bass better", "lowered the noise floor", "had even lower distortion", "changed the soundstage" (ie. interchannel effect and stereo illusion somehow changed!) or "made the dynamics so much more powerful and exciting" than any other without coming to terms with the cognitive dissonance these comments would imply! If one were to truly hear difference such as these, the likelihood is that one did not set things up properly and should consider what went wrong. In fact, none of the asynchronous DACs I've tested at length (TEAC, Light Harmonic GO2, AudioEngine D3, Focusrite Forte, Creative E-MU 0404USB, ASUS Essence One) have shown significant variation in measured analogue output using different computers over the years.**
It's fascinating watching the audiophile market, the build-up of excitement around devices, the ebb and flow of products as they work their way through the audiophile mind-share and supply chain. Like the "flavour of the year" in 2015 with the UpTone Audio USB Regen, a device which supposedly improved USB transmission through a single-port hub, I'm amazed by all the hype around the microRendu recently. Folks, it's basically a low-power ARM SBC*** with Linux-based DLNA/Squeezebox/Roon playback. I think the most interesting part of the whole package is the software flexibility - that's great. But considering the asking price for the microRendu of US$640 (without power supply) for functions I can replicate with the ODROID-C2 for less than $100USD including power supply and some decent USB cables to boot, I see no reason to bother giving it a try. In fact, given how fast the SBC sector develops, one might even try the ~$10USD NanoPi Neo as reported on Computer Audiophile (no video capability like the microRendu) and be reasonably confident that you're not missing anything - kudos to Chris for posting information on the device! I think it's wiser to take the savings and go support one's favourite artists by buying more music.
By the way, I've seen the recent microRendu + iFi power supply measurements done by Amir. My suspicion since I don't have the device to test is that there was a ground loop in the measurement set-up given the very strong 60Hz hum using the iFi SMPS. Elimination of the ground loop would likely have shown no noise floor difference between the various conditions. This of course speaks to the importance of managing one's wiring and grounding which can be tricky in some situations and might need some ingenuity for where and how the components are plugged in (especially in a complex multichannel system in my experience when there are many amps, unbalanced RCA cables, etc...) This is why I prefer balanced XLR gear and cabling through my system when I can. You'll generally know if this is a problem because of audible humming through the system. In any event, I'm rather confident that in another year, the microRendu will be deprecated for much nicer looking boxes with claims of even better sound :-).
On "Everything Matters", Product vs. Process-based SolutionsTo end off, let's just spend some time thinking about the old audiophile adage that "everything matters". On the most basic level, of course! Interconnect cables matter to transmit signal. Power cords matter to power your devices. And of course a well-functioning computer server/transport matters to reliably send data. But the problem presented to audiophiles whenever we come across yet another ad, forum post, or impressed reviewer claiming "better" sounding cables/digital transports/DACs is about the threshold of meaningful, audible differences. With some understanding of how the science works, objective data to consider, and some experience in listening to the various offerings, I do believe the wise hardware audiophile realizes that it's not simply "everything matters", but rather "everything can matter, and not to an infinite degree".
At the most basic level, we have to realize that there are both product-based solutions and process-based solutions to improving sound. It's easy for reviewers and forum posters to make recommendations and talk about product-based solutions; just buy a new, supposedly better product to replace your old one and you'll be happy! It is harder to consider process-based solutions like taking a good look at room construction, equipment placement, acoustic optimizations (eg. sound absorption and diffusion), or room correction (like EQ or DSP-based room correction). These solutions take time, study, and typically measurements to verify an improvement; and they're harder to recommend without knowledge of a particular soundroom and system. I would argue that by the time one has spent thousands on a nice sound system, it is going to be these process-based solutions that will get you further and develop the satisfaction in the "hardware audiophile" hobby. Instead of just taking out a credit card, you'll start engaging in a critical evaluation of the hurdles to overcome, start problem-solving issues, be creative with everything from speaker placement to furniture selection to tweaking with an EQ or calibrating a DSP target.
I truly hope that wisdom builds with the years of experience as we engage in this hobby (and in life in general my friends!). And this wisdom comes with it a certain degree of knowledge, sophistication (like being about to choose product-based vs. process-based ways of improving fidelity), confidence and even certainty in what is true; not easily swayed by every new model, hyped-up product, or unusual claim. Excitability and susceptibility to hype are perhaps valuable characteristics for advertising departments and successful salespersons paid on commission to move product; not the mindset of maturing hobbyists, serious journalists, or thoughtful reviewers.
Remember that stereo audio is very much a mature technology these days. Likewise, computer technology is well understood (it is after all engineered over many generations!) especially for comparatively low bitrate audio data transport. Claims of significantly improved quality whether it be software techniques like MQA, specialty cables, unusual room treatments (like these), or "fantastic" new digital transports really do need to be examined rationally in a sober, objective light. Contentious eye-brow raising claims about sound quality are often so because they suggest that the item runs contrary to accepted science. In situations like these, I think it's totally reasonable to be suspicious and request objective results from makers of these products as to how they propose whatever claimed effect can be audible. Barring the availability of such results as has been the case with hyped up products like the UpTone Regen (notice all the empty, impressionistic chatter by the designer) or microRendu, I do believe audiophiles should be asking questions and expecting real answers before signing up quickly into the hype.
** Note that there was one exception worth mentioning for completeness: the time that I purposely pushed the i7 and nVidia GPU to create a hostile environment with massive heat, acoustic and electrical noise. Sure, it's evidence that noise (EMI/RF) can seep through to affect the DAC, but this is quite atypical operation for audio playback. I'm thinking the only time this may be an issue would be while using HQPlayer and running all kinds of DSP processing while off-loading to an nVidia GPU... Even this should not be as extreme as what I tested! I'll look into this later perhaps.
*** For those curious about the innards of the microRendu, check out the pictures and comment from AbeCollins on AudioAsylum. A SolidRun System on Module (FreeScale Cortex A9) with a small custom carrier board.
Greetings from Beijing!
|A scene from Beihai (北海).|
Hope you're all having a great time and enjoying the music...