For this review we did much of our listening through three very revealing custom-fit in-ear monitors: the JH Audio JH16 Pro, the Sensaphonics 2MAX, and the Westone ES5. Other amps and amp/DACs used for comparison included the CEntrance DACport and the ALO Audio Rx MkI and MkII headphone amplifiers.
iQube Amp: as I suggested earlier, the iQube’s class D amplifier section combines, in roughly equal proportions, a good measure of openness and transparency on the one hand, with a robust, hearty, and full-bodied quality on the other. It’s a winning combination that works well for almost all types of music.
Bass is a notable strong point, with good extension and weight, plus excellent pitch definition. Many amps that claim to deliver this level of control do so at the expense of sounding almost over-controlled and thus bit thin and anemic. But not so, the iQube; it gets the balance of low frequency power and control just right.
Next, the midrange of the iQube likewise sounds well balanced, well defined, and extremely articulate. You’ll appreciate these qualities whenever listening to densely layered material where there are multiple musical threads to be delineated at once. There is real synergy between the low end and midrange of this amp, so that two broad frequency bands seem almost to collaborate, giving the amp a sound that is rich and expressive, but never overblown or in any way given to lush, syrupy-sounding colorations.
Finally, the iQube’s highs sound consistently well extended and revealing, though they can also sound just slightly “dry” at times. On one hand, you’ll hear plenty of treble transient speed and detail, with fine overall tonal balance, all of which contributes to the greater good. On the other hand, you may occasionally hear—at least through highly revealing transducers such as the in-ear monitors used for this test—faint traces of a slightly dry or perhaps slightly mechanical-sounding quality way up high. Note, however, that this isn’t a matter of outright brightness (in fact, far from it) but rather is a matter of a very subtle textural quality that some earphones reveal, but others do not.
In many respects, one could argue that the sound of the iQube amp is what really gives this product its appeal (for which reason some might find the less expensive amp-only iQube V1 preferable to the more costly iQube V2 amp/DAC).
iQube DAC: Not surprisingly the voicing of the iQube DAC section is similar to that of the iQube amp, including both acknowledged strengths and occasional weaknesses. Although the DAC accept data streams up to 16/48 (but not higher), I found that on the whole the DAC sounds better, as in clearer and generally better balanced, than some of the higher res DACs that I’ve tried. The point, here, is not to dismiss this DAC out of hand simply because it doesn’t handle 24/96 (or even 24/192) files—unless, of course, you already own or plan to acquire a large collection of high res material.
I do think that the DAC, more so than the iQube amp, bears the lion’s share of the responsibility for those periodic touches of treble dryness I mentioned above. On a positive note, the iQube’s highs sound at least as detailed and well defined as those of most competing DACs, but at the downside expense of sometimes exhibiting that dry quality which tends (albeit in a very subtle way) to make high frequency content sound just slightly artificial. These performance tradeoffs becomes especially apparent if you listen to well-made acoustic recordings made in relatively reverberant spaces, where the iQube will show you most of the high frequency “air” surrounding instruments and voices, but with a presentation that at times makes natural echoes and reverberations sound more like well-done (but ultimately artificial) electronic reverb effects.
To hear the fine, rich, and expressive qualities of which the iQube V2 is capable, try listening to the title track of Chris Jones’ Roadhouses & Automobiles [Stockfisch]. This well-recorded track highlights Chris Jones’ dark, richly textured voice and intricate guitar work, but also supports Jones with the powerful, soaring growl of Hans-Jörg Maucksch’s fretless electric bass, plus a handful of other supporting instruments.
Jones’ guitar sounds terrific through the iQube, so that the filigreed twists and turns of individual notes and arpeggios are given just the right emphasis—with the amp/DAC contributing a sound that is very clear, but never sterile. The iQube also does a great job of balancing the body sounds and higher harmonics of both Jones’ voice and of his guitar, so that you’ll hear a beautiful and appropriately weighted combination of body sounds and higher-pitched transient and harmonic sounds, with plenty of articulation and definition throughout.