i-Qube review

[Swelled Head]

I recently acquired an i-Qube portable headphone amp from Drew Baird at Moon Audio in Holly Springs, NC. I am submitting this review of the unit because in my view, it is an exemplary product.

My father was an audiophile while I was growing up. I joined him in the hobby, and even in a small business for a while. I've been an avid user of high end home audio gear for roughly 50 years. I have personal experience with high end gear up to, but not including the maniacally pricey stuff. Speakers costing 10k, amps and a preamps costing 3-4k, this is the altitude I've cruised at for years. I don't know much about the stratospheric levels where equipment costs more than my Toyota Avalon, or even my home. Wish I did, but I refuse to expose myself to products I'll never be willing or able to buy. I don't want to become dissatisfied with what I have.

I purchased an iPod Touch a while back, mainly for its non-musical functions, and recently got interested in listening to music on it. I purchased a pair of Ultimate Ears Triple.Fi earphones, and then a pair of Shure SE530s. They're both very good, each with its own, minor tonal flavorings, but little to complain about. Then I ran across a post about the i-Qube portable headphone amp and jumped at the chance to raise the anti for a reasonable cost. Having listened to the iPod itself for weeks, my reactions to the i-Qube are informed by that previous experience with both earphones powered by the headphone output of the iPod. With the i-Qube, or any other headphone amp for that matter, one has the option of driving it with the iPod's line out signal, which I highly recommend, bypassing the iPod's headphone amp circuitry.

The i-Qube is a class D amplifier, which gives it certain advantages, including much improved efficiency. See elsewhere for details. Based on previous experience with class D amplification on my main system, I'm convinced that dollar for dollar, class D amplification as a technology is superior to class A or AB. The i-Qube did not disappoint in this regard.

The i-Qube transformed both brands of earphones dramatically, flattening their response and expanding their sonic image. Headphones usually make music sound like it's happening inside one's head. This little amp threw the image well outside the boundaries of my head, more or less reproducing, in a two dimensional plane, the sense of a large, perhaps unbounded recording space. Presumably, with a true binaural recording, a three dimensional image is possible. In any case the large image was accompanied with greater clarity and separation between instruments, sort of like going from a 35" standard television to a 60" HD screen. It was much easier to follow the separate contributions of each instrument or voice to the music, similar, in clarity, to the experience of live music. But these are recordings, after all. At their best, they can only come very close to mimicking reality, and sometimes even seem more interesting and dramatic than reality, but never quite the real thing. What's required to approach the goal of natural sound is exceedingly low distortion and the corresponding clarity of tone and image that arises from such equipment and properly engineered recordings. The i-Qube pushed the envelope on this quality for me, reinvigorating my enjoyment of recorded music. Certain complex recordings from which I thought I'd exhausted all the details were revealed as possessing previously hidden information. It's been a long time since I've been sufficiently involved in musical reproduction to enjoy the sense of discovery of new details and nuances in music I'm familiar with. I found myself listening to entire albums that I thought I'd become bored with due to over exposure over the years.

A note on headphones: Headphone listening eliminates a source of distortion inherent in ordinary stereo reproduction--cross-feeding of signals from the left speaker to the right ear, and vice-versa. Cross-feed causes image shrinkage, comb filtering of frequencies, and a generalized lowering of the perception of sonic details. IEM earphones further clarify the signal by coupling the drivers directly with the ear canal, very close to one's eardrums. The result is an enhanced sense of tonal clarity and purity. They also make the image plane bisect the head, and with most headphones/amps, the image is a little cavern inside or nearly inside the head. The expansion of recorded space was perhaps a function of the low distortion of the resulting playback. Really low distortion tends to throw a huge image. The i-Qube, particularly with the SE530s, and just slightly less so with the Triple.fi earphones, really blew up the image into a life-like sensation.

My thanks to Drew Baird for his excellent taste in equipment and for making the i-Qube available in the US.

Curt Raney

Addendum: since writing this review, I've spent many additional hours listening at length to both sets of earphones, and many more sources. This leads me to emphasize that the SE530s have a noticeably larger soundstage than the Triple.fi earphones, and to comment that the Triple.fi earphones are somewhat warm, which flatters some music, and is a bit much for others. At lower volume levels, it makes for a nice experience, a little like the old fashioned "loudness" control. However, on some sources, such as pop engineered with a great deal of sizzle, the SE530s focus too much on the highest frequencies. In general, I regard the SE530s as the better balanced earphones in terms of tonality, and have a slight edge on clarity. This is evident from listening to the highest quality recordings by Sheffield, Keith Johnson, and other engineers respected for their efforts to produce natural sound. But I'm not going to give away my Triple.fi earphones. Personality can make some things more interesting, and variety, with limits, is very much the spice of life.

I also need to emphasize that the soundstage size is very dependent on volume and source material. The louder the volume, the larger the instruments' images. I wonder at times whether the sensation that the soundstage is larger than between the ears is to an extent psychological, due to a sense of extreme openness that makes some recordings sound as if the soundstage is boundless, even when I can't say I'm aware of specific sounds coming from outside the boundaries of my ears. It may be that more attention by recording engineers to encoding spatial information, beyond the simple left-right panning of the image, would improve sound-staging enormously. I'm still looking for a source of binaural recordings to test out their characteristics.


Binaural Recordings: Since writing above about binaural recordings and headphones, I read the excellent material on Wikipedia about the topic. Then I checked out some of the references at the end of the article to find some binaural recordings to listen to, found them, and concluded from listening that the information on Wiki about the limitations of earphones vis-a-vis binaural recording reproduction seemed accurate. I had hoped to experience a more or less convincing 3D sound image, and was disappointed, as I was years before when trying out binaural sound on over-the-ear headphones. The image field lacked front to back dimensionality, although the left-right ear boundaries often characteristic of headphone and earphone listening didn't seem very noticeable. Apparently, that's all one's going to get with earphones. Read the Wiki article "binaural recording" for the details.

I liked the binaural recordings, and according to the Wiki article, there is at least one headphone optimized for them, but I'm not rushing out to buy a pair. There are so few binaural recordings available, and there are stereo recordings that approach binaural recordings in their spaciousness, making the soundstage sound less crammed between the ears. I confess to a love affair with natural, acoustic instrumental/voice recordings. Done right, they almost sound like you're there, though I have yet to experience much in the way of front-back dimensionality. The old Capital recordings labeled "full dimensional stereo" are typically very spacious. Several of Stan Kenton's albums were produced in this series, as were some dynamite organ recordings by Virgil Fox. Unfortunately for headphone lovers, so many of the great, popular jazz recordings of the late 50s and early 60s were produced with what we used to call ping-pong effect, isolating instruments on one or the other channel to make the stereo effect obvious to people who didn't know what to listen for. On headphones, I find any sounds that lack some degree of spread between the channels to be annoying. Ah, but so much good music recorded that way. Whadayagointodo?

Curt Raney



August 22, 2008
More on iQube vs. Classic headphone output, and Shure SE530 vs. Ultimate Ears triple.fi 10 pro earphones:

I've been giving evaluation a rest to refresh my impressionator by listening to the iPod Classic for a while, sans iQube. General conclusion after going back to the iQube--the iQube is significantly superior to the Classic's headphone output when driven by the Classic's line out from the DAC. However, the Classic by itself is good enough that I'm not motivated to carry around the iQube when I go out and about. Too much stuff to carry around, too much stuff to keep charged up, etc. The Classic by itself is quite acceptable. The iQube adds a significant boost in clarity and soundstage width/depth. I'll be using it at home when I'm kicking back in my Lazy Boy recliner. One advantage is I can keep it plugged in to a USB charger at home.

Last night, I woke up at 4AM and cued up Pat Metheny's album "First Circle." Metheny's recordings are typically very layered and require great clarity to experience the depth of feeling he puts into them. The iQube added to the musical experience. Then I got back to comparing the SE530s with the UE triple.fi units. It's almost a matter of taste. Parts of the spectrum are more clear and detailed with each. I like the somewhat brighter presentation of the 530s. The mid-bass on the UEs is more detailed and prominent. I suspect that the 530s are more neutral, and the UEs are a little warm, but they're both very, very good and I could live happily with either. I wish I could reach a more definite conclusion for those of you out there who are trying to decide which to purchase.

Next on my agenda: I dug up an adapter for the quarter inch plug on the Sennheiser 650s. I'll be comparing these phones on the iQube vs. my state-of-the art dynahi circuit headphone amp custom built with high grade parts by Drew Baird at Moon Audio. The darn thing weighs a ton for a headphone amp, but it's really clear and neutral. Since I haven't used it for a while, it should function as an interesting comparison with the iQube.

Curt Raney

[dazzer1975]

Absolutely superb first post sir, I hope to read a very many further reviews from your good self.

[tha_dude]

What did you think of opening the case?

[Aurven]

Excellent first post! Welcome to head-fi!

[BigTony]

Can you buy the IQube with the rechargables installed? Safe a huge amount of grief!

[dazzer1975]

Yes you can.

[analogbox]

Nicely done. I very much enjoyed reading your review. Keep up the good work, sir.

[nsx_23]

Got some pictures?

[BigEat]

Nice job. I agree with your observations by the way. Getting the thing opened to replace the batteriies is half the fun.

[BigTony]

Originally Posted by dazzer1975

Yes you can.

So if I buy them off their EU website the rechargables are fitted?
I'm pretty much 'MrBreakIt' in these parts, I'd most likely get my partner to try (but she has a sore hand atm) as I'm well known for just ripping it apart with my hands, and whisper 'Opps - must have broken in transit!' (the only time I was asked to put up sheves in the house I pushed the screw and the screwdriver through the house wall - 'well you said push hard!')

BT

[dazzer1975]

lol.

well, if you are in the us you have to order them from moon audio (I think its moon audio who is the licensed iqube reseller for north america) otherwise the official iqube site run by qables has the option of buying the iqube with rechargeable batteries already installed.

You will need to add the usb charging cable though as the amps dont come with a charger.

[BigTony]

Part amp - part puzzle game!

i'll see how sterling is shaping up against the euro, seems cheaper to import from the usa than buy in europe.

BT

[hatethatgiraffe]

Moon Audio are the official american seller but will not send outside continental America Tony!!
Sucks huh?

[musicmaker]

What a great review. And this is your first post !!

Very well written, enjoyed reading it. Hope to hear more from you.

[ralfale]

Nice review on iQube with the 2 earphones. Hope to see your posting more.