Saturday, 3 July 2021

MEASUREMENTS: Review of AudioQuest JitterBug FMJ. (And on Milind Kunchur's recent RCA vs. XLR paper.)

Hmmm... What does "LESS DIGITAL NOISE" actually mean? After all, noise that's bad enough to affect digital data will result in errors. Obviously, that would be very bad!

Normally, I don't review stuff like this because there's simply little reason to believe these kind of things do anything of value.

I know, this comes across as highly biased right at the start of a review post! But I want to be honest and I wasn't born yesterday so I know there are all kinds of claims in the audiophile world that simply do not pan out. Furthermore, I've had experience with the AudioQuest company (see the Dragonfly Cobalt / Red / V1.2 DAC review a few years back) and know that they have made claims which turn out to be untrue when tested.

Another admission going into this is that I was introduced to the AQ JitterBug back in 2015, and over the years I have seen other tests like the Audio Science Review thread from 2019. Having said this, I am happy to be swayed if I truly hear a difference or measurements show me that I should change my mind.

So, when a local audiophile friend bought the new AudioQuest Jitterbug FMJ ["Full Metal Jacket" - cute] (~US$60, released mid-May 2021) and suggested I borrow it for a week as he went on vacation, I figured it would be fair to give it a try and see if I can run some measurements to provide data to audiophiles at large on this update to the product. I promised him that I would give him my honest opinion.

To start let's look at the box and device:

Nothing fancy in the box. An instruction sheet, 3 month coupon for Qobuz (useless here in Canada), and the unit itself. I think the box art is also about the same as the older model.

It's a small rectangular USB "stick" that measures 1.6cm wide x 1.2cm tall x 5.5cm long including USB Type A male connector (4cm long without the connector). It feels reasonably sturdy in the hand with metal casing, rounded edges, and the rubber USB cover out back is a nice design change from the old JitterBug which is just a plastic thing with exposed rear connector. The rubber cover comes off if I pull it too hard; I could use my fingernail to shove the hinge part back into the slit with a little bit of effort. 

Something I did not like was that the unit rattles a little bit which reminded me of the construction of the Dragonfly Cobalt I previously described. It weighs <20g with thin metal casing. I have not seen any pictures of this device open so have no idea if they significantly changed the circuitry beyond the metal casing. Word on the street is that there has been no change internally.

A look behind the rubber cover - standard USB Type A female connector, good to see gold plated pins inside the connector:

Here it is hanging off the side of my laptop. It is relatively long and could be ridiculously cumbersome if you have a USB DAC sticking even further out:

My old AudioEngine D3 DAC from back in 2014 itself is ~5.5cm (not including male connector) so in total that's sticking out around 9.5cm (~3.75"). Have to be careful if I move the laptop around not to hit anything! Probably best to use a USB extension cable to reduce strain on the port if I want to use this combination.

Something I noticed about the construction was that the angle of the USB connector had a slight downward tilt from the metal body looking from the side. This won't affect function and who knows, maybe it was meant to be like this but the construction looks a little "off". Don't know if other units are the same.

Ostensibly, the purpose of this device is for "data & power noise filtering" as per the product description. Also, within the name is the implication that jitter can be improved. Note that this is a USB 2.0 product so don't stick a USB 3 hard drive into it which presumably will just degrade data transfer speed (did not try).

For more of what the company claims this device does, here's the rear of the box:

Cool, that rubber cap at the back is "carbon-loaded" and apparently dissipates RF noise. ;-)

Knowing this then, from a testing perspective, we should see if noise floor is lower, check for improvements in distortion, and whether this thing affects jitter with DACs. They also talk about funky stuff like "internal noise-intermodulation" and giddily suggests you can buy another one for parallel noise reduction purposes - "a 2nd JitterBug in parallel is always a delightful improvement as it pulls more RF Noise off the USB power bus"... Uh huh... Sure...

I. Objective

First, let's discuss the "materials" for this little experiment. Here are the DACs I'll use with the device:

As you can see, I have my RME ADI-2 Pro FS warming up which is representative of a more expensive "high fidelity" DAC (with ADC) >US$1000 capable of very low noise thanks to balanced outputs. Note that I will use the ADC function for measurements of course. Less expensive, but still around $200 to the right is the Topping DX3 Pro (V2) which is powered by a wallwart and I know from previous measurements that there is some playback jitter. Finally, let's try the old silver AudioEngine D3 (from 2014) sitting on top of the RME. This is a USB-powered USB Audio Class 1 "stick" DAC which is capable of 24/96 hi-res and measurements years ago showed reasonably well controlled noise level (but higher than the other two devices) and low jitter.

In combination with the DACs, let's also measure using a few USB outputs as organized below. Let's get started!


Let's put the JitterBug right off the front USB port of my Intel NUC 6i5SYH computer with WiFi turned on, using the NUC's stock switching power supply, close to the HDMI monitor. Notice that there's a wireless keyboard/mouse dongle on the adjacent USB port that could add extra "noise":

As a first test, let's just run a loopback with the RME ADI-2 Pro FS at highest resolution with XLR cables with and without the JitterBug. For efficiency, I'll use the RightMark 6.4.5 Pro suite at 24/96 which will give us a look at the noise floor and distortions out to 48kHz, more than good enough for audio applications.

Starting with the summary numerical results:

Nothing interesting here. Basically the same results whether the JitterBug was used or not. For more detail we can have a look at the RightMark composite graphs which I've historically used to summarize the data:

This is what "no difference" looks like. Frequency response is flat. The noise floor all the way to 48kHz is clean regardless of the JitterBug's presence. Stereo crosstalk is a function of the interconnect used and the DAC itself rather than bit-perfect digital - nothing abnormal there. No difference in nonlinear distortion on the IMD+N sweep.

So how about jitter from this loopback test?

As you can see, I have the 24-bit J-Test shown above. Let's not waste time on the 16-bit test since we need to have a good look deep into the noise floor to see if there are differences. In light blue/cyan is the 1M-point FFT from the RME plugged directly into the NUC's front USB port, and in red is with the JitterBug. Where the two FFTs overlap, it's black.

In essence, there's no difference. However, if we pixel-peep at the small sidebands around 12kHz +/- 250Hz, we actually see that the JitterBug plot showed a higher signal with red peaks reaching up above the -140dB mark. While minuscule, this does suggest that jitter might have been marginally worsened with the JitterBug FMJ in place!

Okay then... Let's now purposely do something that I don't do when measuring DACs. Over the years, I have discussed the potential for the 8kHz USB PHY noise to be a problem in some circumstances. When I have both a DAC and my measurement ADC on the same computer or USB hub with the output of one connected to the input of the other, noise including this 8kHz noise can be quite nasty, likely as a result of ground loops from the complex interconnections and electrical paths.

So let's now connect the RME ADI-2 to one of the rear USB ports of the Intel NUC, and plug the Topping DX3 Pro into the front USB port. We will now shift to using a shielded RCA cable. Here are the RightMark results +/- JitterBug:

Interesting, a bit of a mixed bag. Numerically with this combination, we can see that the JitterBug lowered the overall noise level a tiny bit by <0.5dB. Notice the 8kHz USB PHY noise poking out as expected along with harmonics. Of note, the JitterBug is clearly unable to clean this up. Apart from that, we can see on the noise floor FFT that plugging the DAC "Direct" into the USB port showed a little more noise with the white tips poking up. Very small, insignificant, differences in the stereo crosstalk and IMD+N sweep not worth worrying about.

And how about jitter?

No evidence here that the JitterBug improves jitter at all. The sidebands around 12kHz remain exactly the same (at least sidebands didn't get worse like above with the RME).

Of interest, this FFT also captured the 8kHz USB noise and the 16kHz harmonic. Notice that the peaks are red! Sadly, this means that not only did the JitterBug not attenuate this noise, but it was actually even a little worse.

The Topping DX3 Pro uses its own power supply, so finally let's try the AudioEngine D3 - a portable "stick" type headphone DAC which uses the +5V power from the USB port itself:

Technical detail: because at 100% volume the D3 clips, I'm measuring at 90% output level.

While again very close, we're not seeing the JitterBug improving the noise floor here. Again, no evidence that the JitterBug can clean up the 8kHz USB noise. Crosstalk and distortion basically identical.

As for jitter:

Nothing different or worth mentioning. Notice that for this DAC, there's a little bit of wide-based "skirting" around the 12kHz signal suggestive of low-level random jitter. The JitterBug is unable to attenuate that. Pixel peeping suggests that the JitterBug added noise below 8kHz just by a smidge.


Let's see if we can make this potentially even more noisy! Here's the JitterBug plugged into a 10-port USB 3 hub which has its own switching wallwart for power, itself plugged into the Intel NUC above:

Notice the ports and blue LEDs are all turned on which I suppose might add extra noise. From left (closest to the power cable) to right, I have plugged into this hub a cable going to my miniDSP (H)EARS headphone measurement jigKingston 32GB USB 3 memory stick, the JitterBug FMJ (with AudioEngine D3 sticking up, shielded 3.5mm phono to RCA cable into RME ADC for measurement), AZIO Bluetooth dongle (with aptX, paired to my phone but not playing during the test), and then another 32GB memory stick. I purposely put the JitterBug sandwiched between the other devices to potentially maximize noise and jitter as might or might not be the case. I trust this arrangement is not considered "best practice" by most audiophiles, and one would not do this while critically listening to music!

For expediency, let's just show the data with the 3 different DACs together, I'll show the RightMark noise and IMD+N graphs (no problems with frequency response and crosstalk), plus the jitter graph of course.


You can see the average noise level of the DACs with RME ADI-2 Pto FS < Topping DX3 Pro < AudioEngine D3.

Noise floor and IMD+N:

As you can see, the XLR output of the RME is clearly superior to the unbalanced RCA/headphone outputs for low noise as one would expect. Notice the 8kHz USB noise especially with the Topping in this set-up. Most importantly, for our discussion here is that the JitterBug appears to make no improvement to noise level nor does it affect distortion in any of these graphs. As you can see, the RME ADC is able to resolve noise level down to better than -140dBFS; low enough that if the JitterBug made a significant audible difference, we should find it.


As with the measurements off the Intel NUC's USB port, we see no evidence that the JitterBug has any ability to reduce jitter compared to plugging the cable directly into the hub. Of note, at least with this USB 3 hub, the measurement with the JitterBug didn't seem any worse on the RME loopback.

Again, we can see that the 8kHz USB noise and 16kHz harmonic with both the Topping and AudioEngine DACs have not been attenuated to any degree using the JitterBug.

An interesting aside: the AudioEngine D3 DAC from back in 2014 is one which I've found to be more sensitive to jitter depending on the USB hub it's connected to (we're still looking at less than -120dBFS so nothing audibly to worry about). Newer asynchronous DACs like the Topping DX3 Pro are more resilient.


Finally, let's run measurements using the Raspberry Pi 3B+ "Touch" device playing from the USB storage you see plugged into one of the ports in the picture below. This is commonly the type of set-up I use for DAC measurements. With a separate playback system disconnected from the same computer/USB hub, we will not see ground loop issues like above.

I'll just use a standard 3A switching power supply for the Pi with touchscreen and WiFi turned on:

As you can see in the picture above, I've already plugged in the AudioEngine D3 DAC to the JitterBug. Test signals were copied on the USB stick, playback software is the recent Volumio v2.882.

For this set-up, I'll test the Topping DX3 Pro V2 and AudioEngine D3 DACs since there's no such thing as running a loopback measurement with RightMark on the ADI-2 Pro off the Pi.

RightMark summary:

Alright, there we go with "proper" measurements of the Topping DX3 Pro and AudioEngine D3 free from general computer and specifically the 8kHz USB PHY noise. As you can see, there's really not much difference numerically at all between a direct USB connection and using the JitterBug.

Here are the noise FFT and IMD+N graphs:

Overall good noise floor for both, 60Hz mains hum highest noise level (still below -120dBFS). At best, perhaps we can say that the result with the JitterBug in this configuration looked ever so slightly better when paired with the Topping DX3 Pro. Nonetheless, there is no meaningful improvement overall, the device does not filter out 60Hz hum and there's no change to distortion characteristics out to 48kHz.

Jitter measurements:

Even though we can easily see the presence of those jitter sidebands, notice that the JitterBug has zero ability to change this on the Topping DX3 Pro.

Wow. Look at how clean/jitterless the old AudioEngine D3 is off the Raspberry Pi 3 B+ streamer! Again, some low-level "skirting" around the 12kHz signal. No evidence that the JitterBug has the ability to clean any of this up.

II. Subjective

I noticed that some of AudioQuest's announcements for this product suggests that using the device will result in "more spacious and engaging sound". Okay... Let's have a listen. I used 2 systems:

A. Headphone: Intel NUC --> +/- JitterBug FMJ --> Topping DX3 Pro --> Sennheiser HD800

B. Sound room: Raspberry Pi 4 "Touch" streaming from Roon server --> +/- JitterBug FMJ --> RME ADI-2 Pro FS R Black Edition --> Emotiva XSP-1 analogue preamp --> Hypex nCore NC252MP amp --> Paradigm Signature Reference S8 speakers + subwoofers

The JitterBug sticking out behind my Pi 4 "Touch" - I have a 90° adaptor for the USB port. (A 1993 Hacken Lee 李克勤 Cantopop album cover on the screen - called Album in fact.)

I spent a couple evenings listening, switching in and out the JitterBug three or four times with each set-up. Instantaneous A/B switching isn't possible so I did the switch as quickly as I could.

Seriously folks, after taking the JitterBug in and out of the USB path a couple of times, it's clear there's no audible difference worth the effort. The novelty wears off very quickly and definitely I am not hearing any "more spacious" nor "engaging" sound compared to what I already enjoy directly through the USB port without the JitterBug FMJ. No differences in background noise level or any impression of "blacker blacks" or other such clichés.

Sorry, no creative subjective fictions of what I heard to describe for you guys. ;-)

Here are the albums I had a listen to those evenings: Olivia Rodrigo's Sour (modern pop), Brian Bromberg's Jaco (jazz fusion), Kaori Muraji's Cinema: Movie Themes for Classical Guitar, and Melody Gardot's Sunset in the Blue.

At least I did not experience any issues with playback or dropouts using the JitterBug. It basically worked and sounded "transparent".

III. Discussions & Summary...

Well, across multiple DACs and various USB ports - the Intel NUC, Raspberry Pi 3B+, 10-port USB 3 hub - as you can see, there is nothing here to suggest that the AudioQuest JitterBug FMJ made any worthwhile difference to audio playback.

Despite me not taking any "audiophile precautions" at all - WiFi turned on with devices, Bluetooth on if present, stock switch mode power supplies, USB hub with other stuff plugged in - there is no evidence that noise has in any way been significantly improved by the JitterBug FMJ. Do not buy this product thinking that it is capable of suppressing ground loops and stuff like the 8kHz USB noise if you run into such issues - there's no galvanic isolation here. Likewise, despite the JitterBug moniker, there is no evidence that this device improves the timing precision of the DACs plugged into it to affect jitter performance in a positive way.

In fact, depending on which DAC was used and with which USB port, sometimes the JitterBug FMJ might even result in slightly more noise or worse jitter. Nothing major, but just the same, why spend money on something that doesn't actually make a difference and just as likely could result in slightly poorer audio output?

Subjectively, I hear no difference when doing A/B listening and I do not feel compelled at all to own one of these. Admittedly, I do not claim to have any super powers but I did receive a "Golden Ears" certificate a number of years back, I have avoided loud concerts through life, and am not quite 50 years old yet. ;-) (Obviously, I believe personal characteristics like age and listening acuity are important for subjective evaluation.)

As you can see in the picture of the box above, this product (presumably based on reviews of the original plastic JitterBug) has been endorsed by The Absolute Sound, Stereophile, the understandably defunct AudioStream, Hi-Fi News, and Positive Feedback. Not listed there, we also can find Darko Audio, What Hi-Fi?, Hans Beekhuyzen ("if you don't hear any difference, you know you have to improve how you set up your stereo", LOL), Paul McGowan of PS Audio and TONEAudio with their accounts of improvements. Likewise, recently this Part-Time Audiophile article with thoughts by Graig and Grover Neville was rather hard to believe including the parts on the JitterBug. Then there's IMO YouTube BS like this.

Stereophile's measurements of the original JitterBug (2015) showed no difference yet claiming that it "improved the sound - which it most certainly did" with no further sense of curiosity to investigate why the reviewer believes such a thing is simply ridiculous. I believe John Atkinson was wrong - he most certainly was.

I would strongly suggest that audiophiles take endorsements and awards from audiophile "news" outlets with caution whether it be very expensive stuff or cheaper trinkets like this.

IMO, it's a shame that writings / videos like these have permeated the mainstream audiophile "culture"/ "lore" so thoroughly. Claims of audibility hidden behind subjective "evidence" are not hard to obtain (or to influence, or to buy). After all, one could always say to the unbeliever that "your ears and gear are just not resolving enough", right? Thus absolving the subjective commentator of need to provide any evidence of what they supposedly heard, or that he could just plainly be wrong.

The fact that there has been a chorus of positive reviews for something as questionable as the JitterBug I believe is an example of how this system of subjective-mainly reviewing is incapable of separating truth from advertising, and in the process treats the interests of the consumer as secondary to the claims of manufacturers. Until this changes, much of the audiophile Industry and its mouthpieces simply cannot be taken seriously by most music lovers. Thankfully, my sense over the years is that audiophiles have become more rational as a group and hopefully can maintain a healthy level of skepticism going forward.

I was thinking about audiophile "snake oil" and how I would classify the JitterBug FMJ. It's probably at best a Class B "Unnecessary Accessory" that provides some high frequency filtering in the circuit path similar to a USB jack with integrated EMC filtering. There's a range of chokes and ferrite beads one can find for USB data and power line filtering (especially for noisy industrial applications) but it would be hard to justify these as helping achieve better sound quality on the other end of a consumer audio DAC! Presumably AQ incorporated a few of these inexpensive parts in the Dragonfly Cobalt which is why they claim the JitterBug is not "needed" with that.

From a marketing perspective, I can see AudioQuest wanting to capture the "cheapo audiophile tweak", "trinket" segment with this product suggesting to audiophiles that it's inexpensive enough to take a chance on, or as some kind of "stocking stuffer" at Christmastime. Smart marketing move I guess. AudioQuest also suggests that you might want to buy 2 of these and plug up an unused USB port. Again, smart marketing move but IMO misleading and definitely "snake oilish". By the way, for giggles, I did a couple of measurements putting the JitterBug on an adjacent USB port and as expected, found no difference at all. I am certainly not curious enough to get 2 of these to try in parallel given the lack of difference even when used in a serial path!

Bottom line: I think it's best to spend your US$60 elsewhere. For example, go treat family/friends to a good bottle of wine - you'll get more enjoyment and they'll love you for it. Giving the money to a good charity will also likely improve the world more than whatever change to the sound of one's system.

I would love to see AudioQuest come up with evidence that this product makes a difference when used in conjunction with a DAC - what equipment they choose, and with what tests would actually be highly informative!

Note that even though the JitterBug failed to show value, there are relatively inexpensive USB isolators out there that could be useful in some circumstances. For example, ADuM4160-based devices are inexpensive and easily available but they are limited to 12Mbps "full speed" - fine for up to 24/96 stereo. Maybe at some point I'll give the iFi iDefender+ a try to see if ground loop elimination can deal with stuff like the 8kHz USB noise while maintaining high speed. There are other high-speed USB isolators (eg. Intona) I might look into later. Historically, I've also tried the Corning USB 3 optical cable, and USB-over-ethernet cable extender which might be useful in some situations.

Big thanks to my friend (who wanted to remain nameless) for letting me borrow this for the week. I suspect he will be returning this after I talked to him about my findings and showed a few of the graphs above.

With all that's done and said, if you still want to give AudioQuest your money, please feel free to use my Amazon Affiliate link here: AudioQuest JitterBug FMJ. While AudioQuest makes a few bucks, I'll also make a few bucks which I will subsequently recycle into buying some CDs to support the artists. Thanks for the charity. ;-)

Cheers (with a glass of that $60 bottle of wine of course)!


As you can see in the measurements above, there are improvements in noise level to be had when using balanced (XLR) output if we look at the RME compared to Topping DX3 Pro (RCA) and AudioEngine D3 (3.5mm headphone) single-ended outputs.

This reminds me of a recent paper by Dr. Milind Kunchur - "Cable Pathways Between Audio Components Can Affect Perceived Sound Quality" (here's a PDF copy from the author) - that shows statistically in listening tests that a short XLR cable output vs. longer RCA cable out made a difference using the same Cambridge DAC. (We've come across Kunchur before with his research on auditory temporal acuity.)

In 2021, apparently we still need research from the University of South Carolina into balanced vs. unbalanced cables to show that the common mode rejection provided by XLR output is beneficial and can be audible!

Notice that Kunchur doesn't even show a standard log audio frequency FFT between the RCA and XLR outputs to help us appreciate the difference in noise floor and the relative amounts of stuff like 60Hz hum. Instead, a linear graph out to 2.5MHz seemed important to the author for analogue audio and human listening?! I don't understand what kind of review process the Audio Engineering Society has to allow an article like this to pass! Hasn't the science behind balanced audio transmission been known since before the 1950's? Maybe it's a slow time for journals given that so much research effort has gone into COVID-19 lately.

Anyhow, here's a summary I posted on an Audiophile Style thread recently:

Posted June 13, 2021:

Yes, the author sets out to find a difference in audibility between 2 cable paths. One with a 2m RCA cable and the other with a 0.5m XLR cable. Both plugged in simultaneously as far as I can tell to the same Berkeley Audio Alpha 2 DAC. Both cables connected to the same Spectral DMA-250S Amplifier.

Potential causes of differences between the RCA and XLR outputs:

1. The Berkeley DAC may perform differently between the single-ended and balanced outputs - distortion levels, frequency response can be different. Even as output level controlled.

2. I didn't see a measurement of the output impedance of the Berkeley DAC and the input impedance of the Spectral amp; I assume they're OK for both balanced and unbalanced operation.

3. Odd that RCA cable longer than XLR. Unbalanced cables obviously more susceptible to noise which is what they found. No surprise. (And no surprise that this could be audible.)

4. Even more strange, why did he choose an expensive $500 XLR short cable vs. $50 RCA long cable?

If we give the benefit to the Straight Wire Virtuoso cable as better built with better connectors since it is 10x the price for 1/4 the length, then he's totally stacking the listening test against the RCA output! And guess what, the RCA output path sounds worse with more noise which he concluded as "However, the electrical measurements conducted here indicate that noise levels may be one determining factor of sonic performance".

"May be"!? Why doesn't he just show us an FFT of the noise floor from the RCA output vs. the XLR from 20Hz-20kHz? Let's see the level difference between the 60Hz hum for a start...

What exactly is the new "scientific" finding here or the uniqueness of this experiment?


Hope the Canadians had a great July 1st, and happy Independence Day to the Americans ahead.

Have an awesome summer enjoying the music, dear audiophiles... 


  1. Great article as always Archimago!

    I think you place too much weight to the relevance of the "mainstream audiophile press". I think the market has moved on long ago. They themselves are now very well aware of the declining "audiophile" demographic. Truth is - they are still there, however most people interested in good sound do not themselves identify with the traditional "audiophile".

    As a side note - have you noticed how (until very recently) - the "audiophile press" has almost exclusively dismissed the humble subwoofer. All of a sudden (and nearly in sync with each other) the audiophile press has started singing the subwoofers virtues? Same goes for room correction and DSP. Where have they been for the past 20years?

    Shouting at clouds,.

    1. Thanks for the note Gordon,
      Yeah the demographic shift is surely happening gradually over the years. As the Boomer generation retires and give way to the next cohort with disposable income, I think perceptions, beliefs, and willingness to follow in the ways of the forefathers will change significantly.

      This is IMO a good thing. New technologies which the older "traditional audiophile" folks might not appreciate - DSP and subs might be good examples of this shift - will provide opportunities for companies to further innovate.

      Everything must change in time, and growth demands this change. I don't think it would be much fun being stuck indefinitely going back over stuff like new-old-stock 1950's vacuum tubes, yet more expensive ways to turn a platter, and just listening to vinyl only ;-).

    2. I am 68, and consider myself an audiophile, and I became one when I was first subjected to an awesome stereo system at about 13 years old. I have been avidly interested in music reproduction and the means to this ever since.

      But DSP or room correction has no place in my system. It might rectify some issues, but I feel certain it would create issues of it's own at the same time. The fewer the components, the cleaner the sound quality. I never use tone controls or loudness either.

      I never felt I needed a sub, but my son (27 years old) begged me to buy one, so I did. After all, he's going to inherit my system ;)

      So I purchased a Rel T/7i and placed it in what must be the most awkward location anyone could think of, simply because I have zero room near my main speakers. About 4 feet to the right of my listening position, pointing towards the diagonally opposite corner (= the left speaker). Strangely enough, the bass sounds like it comes from exactly between the main speakers and I don't hear the sub itself at all. Perhaps this is because I use a low crossover point (about 37-38 Hz), as my main speakers' -3 dB point is 39 Hz. I don't really know, but it works, and the sub adds only about 7-8 Hz below the main speakers, just like I want it to.

      I like Rel Acoustics' approach, as they recommend connecting the sub directly to the speaker terminals. This can be done because the input impedance of the sub is several hundred thousand Ohms, so the sub's impact on the amp is negligible.

      Old school, perhaps I am, but I have been lucky enough to put together a system that sounds truly great, and which is very neutral, yet very detailed and without listening fatigue.

      I steer clear of jitter improvement as I believe it can only be done in the clock, and nowhere else. Plus, in a good system no one can hear it anyway ;)

    3. Hey Duck,
      Thanks for your input and experience! Looks like you've got the system well sorted already with full-range mains capable of significant extension <50Hz. While I like my system to extend down to 20Hz, the reality is that most music does not require this (especially acoustic genres) and it's also because I use the system for movies with LFE that a sub is more "essential".

      Yeah, with a crossover point down in the 40Hz region, no surprise that sub localization is not an issue! Great.

      Ultimately I agree also that jitter performance is a characteristic of the DAC device and its clock accuracy. In fact, this has been shown again and again in these pages where stuff like USB cables, ethernet cables, hubs, JitterBug, different computers, network streamers do not particularly change jitter substantially when we're working with asynchronous modern DACs. (S/PDIF input will be more variable.)

      Even if we can see a change (like the RME off the NUC above with or without the JitterBug), the differences are very small. Even the old AudioEngine D3's J-Test fluctuation using the USB3 hub I doubt would be audible and that's about as much of an anomaly as I have ever seen with a USB DAC (and something like the JitterBug is useless to change this).

  2. LOL - Darko's page is showing an "Access Forbidden" message. Did you warn him about your review?

    1. Hey Daniel,
      LOL. Didn't notice that when I was writing the article so wonder if he just banned this site or links from Blogspot in general!

      Anyhow, I see the URL is still active: "".

      Nope, didn't warn him but I'm guessing my comments over the years must have gotten under his skin (or said things his supporters like AudioQuest didn't like to hear).

      I find Darko and his viewpoints interesting. Here's a guy who's not part of the typical older audiophile writers generation who hangs on to the beliefs of that older way of thinking about digital gear and doesn't really delve into the technical "truths" about these products. He prefers to defer to his audiophile "experts" and pleads ignorance personally. It all just comes across as him being fed what to believe and plays his part in creating infomercials to sell their goods.

      I suspect any person who makes a career out of being an "audiophile reviewer" and takes money within the advertising orbit of the audiophile Industry will need to "kiss the ring" of certain types of beliefs: "bits are not bits", "digital is analogue", "jitter is a terrible thing", "analogue has better resolution than digital", "measurements do not tell you how something sounds", "AudioQuest is awesome", etc... ;-)

      I think when we see that kind of constellation of beliefs in reviewers, it's probably a pretty safe bet that they're involved in some kind of relationship with a certain type of "high end" audiophile industry.

    2. BTW, just to be clear, this is not to say that Darko's content is useless. Much of it is useful and covers some basics of sound system setup and stuff like that.

      Just be careful about the "system", or "culture" of beliefs implied and whether he would be able to truly "hear" a difference like with the JitterBug.

    3. Darko blocks any requests with an HTTP referrer pointing to this site or ASR. Very childish but hardly surprising.

    4. Yeah, that's rather silly.

      Not sure how this is supposed to help matters. In the interest of free discussions as audiophiles looking for truth, what's there to hide?

    5. Don't worry about Darko, Arch. His loss, plus I think he has deserved whatever hits him ;)

    6. Hey Duck,
      No worries at all ;-).

      In all honesty, I think Darko's a smart guy. The problem is I think he knows, that we know, that he knows that the crazy stuff some companies make and advertise really do not work. The problem is that when helping to advertise this stuff (typically with high mark-ups), there's a need to at least pretend to drink the Kool-Aid. I suspect this is also what happens with some others (like JA) when they echo silly stuff.

    7. Lol, very true. But there are many more "guru's" out there that act kind of one-sided in many areas. I simply take their advice with a ton of salt, because after over 50 years with hifi as my main interest, there's not that much they can teach me, at least in general. But the people who have provided the most (truly ridiculous) fun are people like Machina Dynamica etc.
      What they have tried to sell us really cracks me up...

  3. Fantastic finding and sum up Archi!
    But how the hell do you still have the affiliation link when you exposed them like that? lol

    1. Hey Alice,
      Ya never know... Some people might still buy one out of curiosity and find it useful for themselves for whatever reason :-).

      If they do, great, they're buying it knowing exactly what I feel about this device and I'm happy to skim a few bucks with zero ethical concerns since it's a free world!

      I think skimming for dollars is essentially what AQ is doing with these anyways. LOL

  4. I don't remember reading anything positive about this item. I doubt I'm some "golden reader" so it might be just luck. Anyway, always great when the proof is presented for all to see, so again, a big thank you to Archimago.

    1. A pleasure trog,
      Yeah, it's one of these things that on occasion one runs into with some "best of" lists - like Robert Harley's 2017 Golden Ear Awards. :-) Notice that he makes a big deal about Dragonfly Red + JitterBug "is so good that you'd need to spend at least $1500 to equal it". Sure. Interesting that AudioQuest gets quite a bit of superlatives like this even though there's not much technology to these products.

      Since the Red is still available, I wonder if that + JitterBug FMJ might now be equivalent to at least $1750!!!

  5. Well if you don't like that, they have lots of other equally effective items coming down the pipe:

    1. OMG Phil. Say it ain't so.

      Caps for USB, RJ45, eh? A mere $30 for 4 - buying now with both fists. LOL

  6. more fine journalism.

    1. You know, I'm amazed by the author Marshall Nack's "golden ears"!

      Wow, dude claims "one of the easiest A/Bs I've ever done" using these caps. I think this is the best example yet of an individual with either:

      1.) superhuman powers
      2.) who's easily biased
      3.) possibly lying

      Sure, we can imagine:
      4.) those AQ caps work wonders! <-- That would be extraordinary ;-)

      I don't think 1.) or 4.) are safe bets!

      I wonder why he would think that frequency extension could be affected by these plugs and needed to ask his female friend for a second opinion!?

      Pretty sure this ain't journalism either...

  7. I've been an "audiophile" for over 60 years and have spent countless thousands on all manner of gear including high end, low ball and "snake oil" for sure. My experience has taught me that distortion, jitter, frequency response errors etc. means nothing. A good tube amp, speakers or headphone, adds a holographic distortion that I cannot live without. Long live the pre-historic technology that keeps me smiling!

  8. The Jitterbug does not remove jitter because it does not re-clock. I also don't hear any difference when plugging a second one into a computer's second empty USB port.

    It is claimed that the JitterBug filters data and power line noise (and switching noise a higher frequencies) that rides on the signal. I am not an expert in measurements, but can EMI/RFI be measured?

    But I do hear a difference in combinations with dongles such as the DragonFly Red. It removes glare and adds depth.

    As I remember, your could not hear a difference between the DragonFly Red and Cobalt, which, to me, sound completely different - not just a bit.

    Here my thoughts of the JitterBug:

    And the thoughts of my co-blogger:

  9. Here my description of the differences between DragonFly Red and Cobalt. I am not an audiophile but have a thorough classical music education through my childhood and youth....and now I am 58.

    You don't need a golden tongue to taste the difference between wine and water, and it is the same with ears and audio. We are talking the whole big forest - not trees. But the difference between these two devices is quite big to my ears.