Heir Audio 4.Ai Universal In-Ear Monitor

I have to admit, I haven’t always been a huge fan of universal In Ear Monitors.  I had some bad experiences a few years back that left me a little jaded.  The fit can be tough and it seemed that bass from some of the old designs was a little unpredictable.  I found that a few of the tube-shaped IEMs had a tenancy to slip around, and depending on the fit I would get big boomy bass or sometimes barely any low end at all.  Movement in the ear canal and poor fit can sometimes lead to ear discomfort.  When I got a chance to try out the Heir 4.Ai universal In Ears I had a bit of a revelation.  The outer design and extremely wide array of earpieces gave a much more comfortable fit than I had experienced before and best of all, they delivered consistent sound every time you put them in.

Heir distribution in the United States is relatively new.  Originally based in Canada and produced in China, official US distribution started in August of this year. Heir offers a somewhat unique spin on IEMs in that they offer the 4.Ai in both custom and universal fits.  The unit I reviewed was the universal fit obviously, and you should take some caution in translating any of this review’s sound observations directly to the custom version.  Custom IEM have a different seal and fit which could equate to a slightly different sound, but I did not have both versions on hand to verify. The universal fit 4.Ai comes in around $400, while the custom version will run you roughly 300 more clams plus ear mold costs($60+).  The Heir 4.Ai utilizes 4 balanced armature drivers per ear to generate sound, two for low, one for mid, and one for high frequencies, hence the “4”Ai.  Top-of-the-product-line customs for Heir ring in at 8 drivers ($1,300), but they also offer a 6-driver version ($1,100).

The Build

The 4.Ai’s are designed like a good pair of customs.  The replaceable cable placement (above and over the ear) alone gives the Heir’s a massive leg up on some it’s cheaper universal counterparts.  The cable weight pulls less haphazardly in this orientation and feels much more comfortable in mobile situations.  I would still recommend a cable clip (like I mentioned in the Portable Audiophile Rig) to help alleviate any unwanted cable noise and reduce the risk of the IEMs accidentally getting pulled from your ears.  The 4.Ai’s are every elegant in appearance and surprisingly light to the touch.  Traditionally I run with clear IEMs, but the 4.Ai’s Amboyna faceplates and deep purple acrylic shell was a welcome variation, very upscale.  The pair I reviewed came with a serious collection of customizable tips, much to my ears delight.  The medium tips worked best for my giant ears, so the large version does leave some room for people with exceptionally large ear canals.   It’s really important to get the fit right.  Not only for comfort’s sake, but sound quality can be adversely affected with an improper seal.  The overall shape of the unit fits very comfortably in the ear.  Noise isolation was typical for a universal with replaceable tips.

The Sound

Treble and clarity can be a tricky thing.  Sometimes they can dance together so closely you can be convinced that one is the actually other.  Every so often I will come across a product that feels like the treble has been pushed forward in order to create the illusion of clarity, but upon further inspection, the imposter is made. The real secret sauce is when you have amazing clarity throughout the spectrum, and then season treble to taste. The Heir 4.Ai has struck an even keel between the two.  I found the treble to be slightly forward, but clarity was some of the best I’ve heard for an IEM in this price range. If you are a fan of treble, you should give these IEMs a listen. I found the treble to sparkle without delivering any unwanted fatigue or anomalies.  The 4.Ai delivered just the right amount of detail and air surrounding the hypnotic flute performance on Jeremy Steig’s Howling for Judy.

As I have alluded to before, bass I hard to get right with IEMs.  A lot of manufactures opt for a more bass-forward presentation.  When compared to a pair of Jerry Harvey Audio JH5s ($400) the 4.Ai didn’t share quite the same low-end expression. The Jerry Harvey sound seems to contain a little lift in the bass section to my ears.  A larger section of  a typical bass line is accentuated on the JH5, whereas the Heir feels more like grabs the lowest notes best.  This not necessary a negative tradeoff, the comparison could be translated as a little less mushy to some.  The bass from the 4.Ai is not anemic by any stretch. Extension is quite good but as with many headphones, sometimes it needs a little volume to perform it’s absolute best.  For those familiar with the Jerry Harvey flagship, the JH16 ($1,150) was more detailed overall at 3X the price, but far less neutral than the 4.Ai, especially in the bass section.

The Bottom Line

If you are looking for a universal In Ear headphone in the $400 price range and prefer an ever-so-slightly treble forward presentation the Heir 4.Ai is a must-audition.  Quality design, comfortable fit and superb detail make this IEM a mobile audio treat, and not just because it looks like a piece of delicious candy either.

www.heiraudio.com