Go back in time to 2007. Headphones were still very much a fringe hobby. Sites like Headphone.guru and InnerFidelity, catering to this small (but even then, growing) segment were nowhere near as prevalent as they are today. Enthusiasts mostly got their info from forums like HeadFi or the occasional review in Stereophile et al – usually covering something mainstream like a Grado or Sennheiser headphone. Headphone amps were available from a small variety of makers, but nothing remotely like the broad selection we have access to today.

2007 was also the time we first became exposed to an interesting little device called the iQube, from a small Netherlands-based company named Qables. A portable headphone amp, the iQube had a very unique architecture compared to other devices on the market – class D amplification courtesy of Bruno Putzeys (Hypex, Mola Mola) and Guido Tent (TentLabs, Grimm Audio). This was unprecedented and remains so to this day. The iQube was hailed as being supremely neutral, with see-through clarity and transparency that surpassed pretty much everything else on the market. The downside? At roughly $500 it was considerably more expensive than competitors in the portable segment, which tended to go for hundreds less. Still, many found it worth the expenditure for the sound quality it delivered.

Another interesting thing about iQube – it never stood still. As the market grew and user’s needs expanded, so too did parent company Qables keep enhancing their product. 2009 saw the release of the iQube V2 which expanded the concept by adding basic USB DAC functionality on top of the existing amplifier section. It being 2009, the fairly simple USB section ran in adaptive mode and topped out 48kHz – which was par for the course given the era. To mitigate this limitation, an asynchronous sample rate converter helped bust jitter, resulting in surprisingly competent sound considering the limitations involved. A few years later we got the V3 which kept the same USB input chip but offloaded D/A conversion to a separate DAC, and also added an SPDIF input capable of handling hi-res PCM up to 24-bit/192kHz. This made the device more competitive in terms of DAC quality. It also had various behind-the-scenes upgrades including higher capacity batteries. These improvements didn’t come free, and by the time we got to V3 I believe the asking price was $799. To keep things in perspective though, I’d say people were more accustomed to increasing their budget by then, as compared to when the original iQube dropped.



The topic of this review is the latest iteration of iQube compact reference device – note I don’t refer to it as merely a “portable headphone amp”, because it’s more than that by now. The designers skipped the V4 designation and jumped to V5 instead, presumably to emphasize the amount of improvements poured into this model as being more significant than prior updates. Interestingly, the price actually dropped by $100 to end up at $699. More features for less money is always a welcome development.

Let’s break down the V5 in terms of function. It’s a portable amp, obviously, with 3.5mm analog input and output. Run it straight from the line out of your favorite DAP and you’ll get many dozens of hours worth of play time – Moon audio lists 40 hours, while the iQube website shows 70, and this obviously depends on volume. It’s also a DAC, with a new XMOS-based asynchronous USB input handling up to 24-bit/192kHz signals as well as DSD64 and DSD128 via the DoP method. SPDIF input capabilities remain on board, using either a full size Toslink plug or else via adapter for the 3.5mm minijack to enable coaxial digital input. The gain switch also remains, this time set to 6 for high gain and 0 (unity) for low gain. To my ears this is an improvement over the other versions where low gain was 2 and high was 7 – that’s a bit more than we needed, sometimes resulting in unnecessary hiss with sensitive IEMs.

We also get iDevice compatibility which requires the Apple Camera Connection Kit used in conjunction with the bundled USB cable. This allows for native playback via Apple’s software or your favorite app such as Onkyo HF Player to unlock FLAC and hi-res goodness. Android support is not officially mentioned but I’ve heard confirmation of successful pairing with at least some HTC and Samsung devices. Android is finally a viable audio platform now that they have several apps to choose from, and it’s only getting better as time goes by, so devices like the V5 are very welcome.

Last, but certainly not least, is the revamped battery. Prior models used 4 AAA batteries. They shipped with nickel-metal hydride (NiMH) rechargables which could be topped off via USB. The first version could also be swapped for disposables – the cheaper alkaline type or the expensive but long lasting lithium variety. Subsequent revisions did away with that feature. V5 loses that style altogether in favor of a lithium-ion alternative. This decreases weight by a small amount, but more importantly does far better with holding a charge when not in use. NiMH batteries have a self discharge rate of roughly 4% per day. Leave your device sitting for a while and it will run down all by itself. Self discharge for LiON is orders of magnitude better, at somewhere around 2% per month. So while we may be slightly down from the 80+ hours of play time on the original iQube, we at least have something to show for it.

The V5 actually has quite a number of other improvements under the hood. The output stage has been completely overhauled, new 4-layer PCBs are in play, a whole new power supply supports the LiON battery, and of course the DAC section is totally redone. Basically the only thing remaining from the last version is the enclosure. So despite appearances, skipping all the way to V5 does seem to make sense after all.


Hans Oosterwaal, head honcho of Quables, tells me his goals for the V5 project were threefold:

*First, keep the same sonic characteristics as its predecessors. No drastic changes in voicing to disrupt the iQube heritage, meaning no surprises for those of us who spent time with the prior models.

*Second, long stamina between charges, especially as it pertains to the digital inputs. Significant improvements on the DAC side mean users are far more likely to take advantage of that function, making battery life more critical than ever before.

*And third, improved ability to drive high impedance headphones as compared to its predecessors. If the V5 is to be taken seriously as an all-in-one dynamo, it really shouldn’t stumble with popular headphones from Sennheiser and beyerdynamic, no matter what the load is.

Hans is confident they succeeded at all three tasks, though of course everything is a compromise on some level. I asked him what headphones were used while developing the V5 and he answered, essentially, “all of them”. I’m exaggerating a tad, but when you’ve tested with Sennheiser, beyer, HiFiMAN, various custom IEMs, etc, you’ve pretty much covered all the bases. The goal, if achieved, is for a compact and elegant device that can do it all both at home as well as on the go, regardless of ancillaries. Was that goal successfully met? At the risk of spoiling the suspense I’ve worked so hard to build….. yes. Yes indeed.


My review unit came courtesy of Drew Baird, owner of North American distributor Moon Audio. Drew was kind enough to send along some of his excellent cables to support the V5 in my particular system, so I was up and running right off the bat. Note that Qables does include several basic cables in the package, so specialized cables are not necessarily needed to get you started – but you may find you want something later as your needs become more clear.

I started out by using the V5 as a simple portable amp, via the analog input. I fed it with a lowly Sansa Fuze using a line-out dock cable I threw together years ago. Even with this relatively pedestrian source, the resulting sound was clean, clear, and very full bodied compared to running the Fuze alone with no iQube. My 1964 Ears V3 and Noble 4C CIEMs both sounded excellent, and I could happily live with either combo for on-the-go listening goodness.

That was just the start though. The Fuze, as good as it is for the price, is far from a high-end source, and probably not a realistic choice for a $699 partner. Something with more audiophile aspirations is called for to get the most out of the V5’s brilliant class D amp section.

I have quite a few premium DAPs laying around for a comparison review I’ve been slowly working on, so the iQube was very helpful. I could listen to the DAP via internal amp alone, and then switch to line-out and listen via iQube. This allowed me to isolate each device’s DAC performance – the neutral, ultra-transparent sound of the V5 really let the character of each device come shining through, which also gave me insight into amp section of the DAP (since the iQube was now replacing it).

Fiio’s X5 is fairly powerful through its own headphone stage, but I don’t find it particularly refined. In fact it’s a little rough around the edges, sounding muddy and dull, lacking definition, and just generally not impressing me all that much. The power is welcome when using full-sized headphones but aside from that it’s not really impressive when used with mid to higher end IEMs. The DAC section of the X5, in the other hand, is quite good indeed, as the iQube/X5 combo allowed me to hear. From Beethoven to Blindside, Budgie to Bacharach, this combo delivered wide open transparency without veering into sterile, analytical territory. I found this combo worthy of stepping up to my finest CIEMs such as the Lear BD4.2 and Noble K10. The noise floor, or should I say lack of noisefloor, was perfect – I couldn’t ask for anything more. This is not something portable folks like to talk about, but I find that most portable amps have at least some minor hiss, even if it’s hard to hear when music plays. Not so the iQube V5.

Switching to the AK120 II from Astell & Kern, I noticed a much smaller gap between internal amplification and the iQube. The V5 was somewhat more open sounding, giving a more three dimensional soundstage as well as slightly improved low end texture. But the AK120 II was certainly no slouch when used on its own, in particular when driving easier loads such as the JH13 FreqPhase or Ultrasone Edition 12. I’m not sure the small improvement is worth the added cost plus the considerable bulk of packing both units for portable use. At $1,699 the AK120 II is significantly more expensive than the X5 paired with iQube ($1,049 for the pair), so it isn’t really a fair fight anyway.

However, there’s a different way to approach the X5/iQube combo that pays significant dividends. Drew had sent along a nice Black Dragon cable for making a digital connection between Fiio and V5. This offloads D/A conversion duty from Fiio’s internal PCM1792 to a Cirrus CS4392 on the iQube. Now, the TI PCM1792 is theoretically the superior chip if judged by specs alone. But we all know (don’t we?) that the actual DAC chip itself is just one part of the puzzle, and many other factors are involved in determining the final result. In this particular case, the design featuring the “lower end” chip ends up being very obviously superior. While I already enjoyed the X5 via line-out, the digital connection was better still, with improved low-level detail retrieval and a real sense of coherency that I typically only associate with more expensive gear. I don’t know exactly how much Moon Audio charges for this cable, but whatever it is – it’s worth it for the improvement it brought to this combo. The AK120 II or even the mighty AK240 has a difficult time keeping pace with the admittedly bulky but considerably less expensive duo. Yes, you have to put up with the clunky X5 user interface, so that’s a downside, but in terms of pure SQ the combo is hard to beat. Using AK120 II as transport to the iQube brought a very small improvement – small enough where I could hardly notice it, and definitely wouldn’t pay extra for it. But the user experience on the AK120 II is so drastically better that it’s hard to go back to the Fiio after sampling what Astell & Kern can do. A good compromise would probably be the AK100 II used as transport, but I didn’t get a chance to try that one.

I then switched to something I do on a more regular basis which is listen at home on a decidedly non-portable setup. Using a very nice Blue Dragon cable supplied by Drew, I connected my Aurender X100L music server via USB, and it recognized the iQube instantly. I also tested with a MacBook Pro (OS X Mavericks) and an HP Elitebook (Windows 7) and had no issues on either side. This is generally my experience when using XMOS-equipped DACs with their mature drivers, though I can’t speak for any headaches caused by the newer OS X Yosemite and its demand for signed kernel extensions.

Pairing the iQube with a relatively easy to drive Grado PS500, the result was impressive: a lively, in-your-face presentation without going overboard, and very nice bass slam for a Grado. Soundstage width was only moderate but that’s never a strong point on Grados anyway. I like how the iQube brought out what I feel is the essence of the PS500 – Grado excitement, without being overly aggressive like most of the other Grado models. I just sent back another DAC/amp unit (similar in price to the iQube) without a review, because its aggressive coloration made the PS500 sound more like a Grado RS-1i… which I don’t consider an upgrade.

Grados are easy to drive, as are the various custom IEMs I used, but what about more difficult loads? I tried an Audeze LCD-2 (the last pre-Fazor version) and again the results were impressive. Even on the low gain setting I got plenty of usable volume range, making the big planar drivers jump with authority. Did it have the same oomph as my multi-watt Auralic Taurus mkII or Violectric V281? Nope. But it certainly didn’t sound underpowered either – the sense of control I get with those larger amps was still largely present, resulting in a very satisfying performance overall. I don’t know whether to blame the class D amp section or the async DAC, or perhaps a combination of both, but this result left me with a smile on my face larger than the iQube V3 ever did when driving the LCD-2. I remember thinking that combo was enjoyable, but this setup was really something special.

While I got similarly impressive results with the HiFiMAN HE-400, the HE-500 seemed a little thin compared to normal. I’d say the iQube is a good but not great  match in that case. I also didn’t love the combo with my Alpha Dogs – things sounded a little shouty and uncontrolled compared to my usual amps (which, again, have far more power on tap). This is the one area where I feel iQube is outshined by some competitors. There are some portable amps which deliver significantly more juice for these difficult loads, and one of those types is probably a better fit for that type of use. I imagine the newer HiFiMAN HE-400i, as well as the upcoming Audeze EL-8 models, should do fairly well as they have lower requirements than the Alpha Dogs.

On the other hand, full sized cans from Sennheiser and beyerdynamic sounded excellent. If we recall the design goals of the V5, one target was to increase the ability to drive high impedance models. Despite the modest power ratings, I do find the V5 quite capable with the HD650, HD800, and even the 600 ohm beyerdynamic T1. It does bring out the true character of each model though, with no sugar coating involved – so the HD650 will be rich but slightly dark, the HD800 ultra-detailed but also a bit bright, and the T1 generally well rounded yet slightly peaky at times. If the goal is to cover up these traits, look elsewhere. If, on the other hand, one desires a clean, honest representation of what each headphone is capable of, iQube V5 is the smallest, most versatile box I’ve encountered to deliver those results.

As good as the class D amp section is, I have to also tip my hat to the DAC portion. It seems very balanced and neutral, providing a solid base for the amp stage to work with. 320k mp3 from Spotify was revealed to be lacking, good enough for background music but not the greatest for primary listening. But Rdio, with their superior 320k AAC compression, was perfectly acceptable. And lossless streaming from Tidal and OraStream Classical HD were very pleasing, as they should be. Thanks to DSD capability, I was also able to play my favorite albums such as A Love Supreme, or Living by Jan Gunnar Hoff, or Acoustic at the Ryman from Band of Horses. Not to mention the fairly deep catalog of classical works in DSD. I still would like to see DSD have a more broad library outside of “audiophile” type music, but there’s plenty of good stuff to be found if one looks closely and is willing to venture outside their usual musical leanings. And the iQube V5 sounds tremendous with all of it.

Nits to pick? Not many. I admit the light weight was a bit off-putting at first – I expected something more solid and confidence-inspiring for $699. But that runs contrary to its design as a portable device, so in the end that complaint is unfounded. I would have thought micro-USB would be a better choice compared to the now outdated mini-USB jacks on board. Perhaps there’s some advantage to the older type that I’m not aware of. Realistically though, the lack of driving power for demanding planar magnetic models is the only legit stumbling block I can muster against this otherwise stellar performer.


Final Thoughts

The iQube V5 caught me by surprise. I knew the amp section would be quite good based on past exposure to earlier models, but I wasn’t prepared for the improvement the team managed to squeeze out of it. And that DAC section? One of the very best I’ve heard in a compact device like this. Seriously – it’s a very impressive accomplishment. Tying it all together is the straight forward, intuitive design, which I had up and running in about 30 seconds flat. Contrast that with Chord’s popular Hugo which, despite superlative sound quality, is frustratingly complex to interact with.

Speaking of Hugo – I see the iQube V5 as a viable alternative which trails a bit behind on sonics but makes up for it with size, weight, design, and – importantly – price. I doubt that’s the competition Qables was shooting for but darned if it doesn’t make a whole lot of sense to consider. I just can’t imagine many folks being disappointed by the little V5. Giant killer? I’m not a fan of the term but the implications are certainly there in this product. When I consider all the improvements to be had for just $200 more than the original iQube, the V5 is very easy to recommend.

Thanks to Moon Audio for lending us the iQube V5 for review.


Moon Audio
106 Brady Ct.
Cary, NC, 27511

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John Grandberg

John is a headphone enthusiast (or geek, take your pick) who enjoys headphones more than speakers because (A) they don't bother his family when he listens late at night, and (B) they aren't affected by poor room acoustics. John can regularly be found contributing over at InnerFidelity.com

  • john grandberg
  • 2015-04-03 10:30:48
  • I wasn't blown away by the iDSD and I've heard it on two separate occasions. Their marketing is very aggressive, and I do think the robust feature set is pretty impressive.... but I just don't love the sound. It's good, sure, but not great imho. I suppose with a difficult to drive headphone the iFi might be preferable, but in all other cases I'd take the iQube V5 any day of the week!
  • Reply

  • Kurt Hertel
  • 2015-04-02 17:04:22
  • I would think that the toughest competition for this device would be the Ifi micro iDSD, especially at $200 cheaper. The form factor is the only place the micro might not be preferable.
  • Reply

  • john grandberg
  • 2015-04-01 03:53:25
  • Sorry, I don't have the TH900 here any longer. Based on experience I'm reasonably certain it would drive them well. Beyond that I can't really speak to exact performance characteristics or synergy.
  • Reply

  • Richard Cai
  • 2015-03-31 22:51:09
  • Hi, thanks for the review, just want to know if you tried to use IQube V5 to drive TH900.
  • Reply

  • john grandberg
  • 2015-03-26 17:53:12
  • Oooh, tough question. I love the Concero HP and recommend it frequently. After a tough battle, I'd have to say it trumps the iQube V5 by a VERY slim margin. However, the V5 has way more features which could easily make it the better choice. Really depends on your situation more than anything else.
  • Reply

  • john grandberg
  • 2015-03-26 17:50:03
  • Sorry my experience with Cypher Labs dates back to their very first model, and it's been years since I used it.
  • Reply

  • Stephen Fabb
  • 2015-03-23 12:25:29
  • As a former iQube V3 user, I'd be interested to hear your opinions on how the iQube V5 compares to the recently reviewed Resonessence Labs CONCERO HP; they're similarly priced, sized and specced, so does one offer more, in terms of sound quality, than the other?
  • Reply

  • Anthony Kimball
  • 2015-03-23 09:23:05
  • Thanks for the review!! I was thinking that the natural comparison would be to the Cypher Labs line of amps/dacs. I'm kind of new to this segment (I only have a 1st gen Fiio x3 & a Dragonfly as my reference) but I am curious about the higher end... Thanks again!
  • Reply

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