The Astell&Kern T9iE is very neutral, with just a hint of bass elevation. Smooth, clean notes render a vivid and detailed soundscape.
Treble is relatively gentle. Yet there’s enough energy and bite to suggest peaks higher up the range. It creates an airy, revealing signature, with lovely sparkle.
Vocals have a clear and sweet tone. A hint of coloration from the bass steers things away from dryness or sterility. The notes aren’t overly thick, though, conveying a nice sense of transparency.
Midrange instruments are well-balanced, possessing both body and detail, richness and sharpness. While the T9iE is not the most aggressive IEM, it has adequate crunch for electric guitars. For the most part, though, the presentation is more about fluidity.
As I said earlier, the bass is forward in the mix, but only just. The T9iE is not for bassheads. There are times when it can disappear into the background. When it is there, however, it fills out the signature, warming the timbre to a lovely degree.
The soundstage is rather cube shaped, with admirable size all around. Imaging is top notch, element separation is well above average, and the resolution gets the job done. In these technical merits, the T9iE stands strong, but I wouldn’t say it “stands out.” While it doesn’t disappoint, there is vicious competition at many different price points.
In this genre of sound, and for the money, the DUNU DK-3001 Pro ($469) is hard to beat, if not impossible. It portrays a more natural tone, with softer treble and even greater transparency. Somehow, it also manages finer resolution and grander soundstage. The only thing I’d say Astell&Kern has over DUNU is that single-driver coherency some folk require. If you’re like me, though, and don’t find hybrid IEM’s “incoherent”, then the DK3001Pro is a great way to save some money.
That said, there is something magical about the coherency of this dynamic driver: The Dream XLS by DITA Audio ($2,299, Review HERE). All three of these IEM’s share much of the same signature. They’re neutral-warm, smooth, and relaxed. They are neither treble monsters nor basshead paraphernalia. They walk a delicate line. While each of these IEMs do a wonderful job, it may come as no surprise the most expensive does it on a whole other level. To my ears, they exemplify the sound I crave. If you can afford it, The Dream is the one I recommend most. If not, don’t weep too bitterly, Astell&Kern’s T9iE is not THAT far behind.