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The Review of Heir Audio 3.Ai&4.Ai

Heir Audio is a quite a unique company, they started off in the world of Custom In Ear Monitors which proved very well for them and in this state the company became quite well known for their CIEM but they decided to do what other CIEM companies had done, which is move into the world of Universal In Ear Monitors. Now their goal was to create a Custom Universal In Ear Monitor which sounds impossible but they did with their 3.Ai and 4.Ai. Both these were brought to light by their marketing but mainly thanks to the Head-Fi community supporting these two UIEM’s and here we are with them. The build quality of the Heir Audio 4.Ai is fanominal, by that I mean they are just amazing. I love it when companies go further than other companies to create their products and here is another example of this. The sound quality, this is going to be easier than my V-Moda M-80 review because the sound of these are almost perfect. So for my testing I used my iBasso DX50 and the headphone output on my Hi-Fi Stereo Amplifier which is a very neutral output. Now these sound in no other word but neutral, the Bass is very detailed but in no way overpowering or even punchy because you will get the amount of bass the song has in it and no more which can be problematic for bassheads but I am NOT a basshead and I love neutral/reference level sound.

[Review] Heir Audio Tsar 350

Pros: Beautiful aesthetics, build quality seems great, excellent clarity, and great detail retrieval while remaining forgiving, to a degree.

Cons: Needs an amp, memory wires are a pain to deal with at first, a bit too bright at times, bass could use more sub-bass weight, I found it a bit difficult to get a great fit until a lot of tip changes, and soundstage needs more instrument separation.

Style: Over-ear IEMs

Tonal Balance: Slightly bright and aggressive with great detail retrieval.

Preferred Genres: Jazz, acoustic, and anything mastered wonderfully.

Amp: Required, bass is severely lacking when underpowered.

Listening Set-Up: Musicbee -> Schiit Modi/Magni stack.




Given that I don’t think the Tsar 350 were ever designed with sitting on a retail shelf, I find it a bit difficult to even comment on the packaging. The packaging is simple though, the IEMs and accessories are tightly packed into a hardshell case which bares the Heir Audio name and logo. A slick cardboard sleeve covers it on the outside, but fits loosely and slides on and off easily.


The hardshell case consists of a hard plastic with a soft foam on the inside. Included is a set of duo-flanged tips, harder mushroom shaped tips and a set of softer blue colored tips which have the nozzle split in half, a pair of cables and the IEMs themselves.


Despite likely never being intended for the retail side, the packaging comes off nicely and the hardshell case is much appreciated.


Design and Build Quality


Aesthetics are purely subjective, but boy these are beautiful IEMs. Mine came with a slightly stained and polished burl that adds a sense of class to the IEMs when placed in the ear with logos only visible when unworn. The braided cable also adds a level of sophistication. Based on looks alone, these may be the nicest IEMs on the market. Classy is the word that best describes these.


Build Quality

The beautiful housing is made of black plastic with the outer, visible, portion being a wooden burl of sorts. The IEMs are light and seem very well constructed. The lightness of these really inspires confidence in-case they are dropped. The nozzle is small and protrudes from the housing. On top of the IEM are two small holes in which the detachable cable plugs into, blue for left and red for right. The plugs of the cable don’t sit entirely flush so they are visible when plugged into the IEM, barely. The cables seem well-made, but the right wire cuts in and out sometimes when positioning in my ear, Heir has been rather quick to replace it though. I should mention that the cable, otherwise, works fine once in place. In-fact this is my only complaint about the build and the easiest to fix.


Fit and Comfort

It took me awhile to find the tips that formed a proper seal in my ear, but thankfully there are a good amount of tips included. Even after finding proper tips I have a bit of trouble getting a good seal sometimes, but it’s becoming less of a problem the more I use these. Once inside the ear, the comfort is average. No problems outside of the ear, but the tips irritate the inside of my ear over time. I find it hard to wear these for more than two hours.


Sound Quality



I’ve used the Tsar 350 for at least 75 hours and have found that it is very picky of its source. Straight from an iPod these sound bassless, though the high-end and mids don’t suffer. With my Schiit Modi/Magni I find that these are great. I noticed no signs of burn-in.



The lows are a mixed bag. At first I felt satisfied, then I felt that they were lacking, and then I realized that the lows are entirely dependant on the recording. If the recording seems bass shy then the Tsar 350 will highlight this due to the emphasis on the mids and highs. That doesn’t mean that the Tsar 350 will satisfy bassheads on a proper recording though. The sub-bass is present, at times, but is easily lost when there is a multitude of instruments, especially with a mid-focused recording. The sub-bass isn’t satisfying because it’s very shy, in-fact at times it’s impossible to hear.


The mid-bass seems better off, but it’s not emphasized at all, thus when listening to an indie-rock band where mids are the focus, the kick drum can become lost. At times I feel that the thump of the bass drum is satisfying and natural, while others I find it lacking. The same can be said with the bass, though I find that the kick drum and bass are fine on songs like Pink Floyd’s Money.This is a problem with the recordings though as the Tsar 350 are picky about recordings and will only feed back what it’s been given.



I feel that the Tsar excel in the mids and highs, notably with vocals and acoustic tracks. I can’t say that I’ve been astounded by electric guitars or synthesizers. The Tsar 350 seem best with acoustic recordings where there is little instrumentation. In-fact it excels there. With a well-recorded album that has little instrumentation, the vocals are clean and intimate, acoustic guitars sound natural and the Tsar shine. When it comes to modern indie-rock I find that the Tsar 350 point out the recording flaws and suffer from seeming congested. After listening to many songs I’ve pinpointed it to the Tsar simply being very picky about the source material. The Tsar will highlight any flaw in the recording and amplify it, but at the same time making it listenable, just not enjoyable.


The highs excel though, even with a touch of sibilance. The wailing guitars of Pink Floyd and the trumpet of Miles Davis sound crisp and clean with no signs of distortion. Boy does Miles’ horns sound nice.



The presentation of the Tsar 350 is what I feel to be where they perform their weakest. The Tsar 350 presents the music rather flatly. I get no depth in the soundstage and the instrument separation seems average at best, often times feeling congested in modern recordings. I feel as if I’m observing the music, rather than being a part of it. The soundstage is wide, but it needs more depth and instrument separation.



The Tsar 350 are great headphones, but highly specialized. When the Tsar are paired with a good amp and a proper recording they shine. With bass heavy genres and many modern recordings I feel that the Tsar's potential is wasted. If you are going to listen to the recommended genres often, then I recommend the Tsar. The Tsar 350 are clinical and really allow those painstakingly mastered albums to shine through. These sing with those recordings and a proper amp. If the majority of your listening is modern indie rock or less than stellar recordings then I suggest avoiding these as the Tsar can be punishing on those poorly mastered and recorded albums.


The Tsar 350 currently retail for $399 and at that price they make a welcome addition for someone who strives for detail and clarity. Come see more pictures here.

[REVIEW] Heir Audio 3.Ai and 4.Ai

Packaging, Accessories and Build Quality

Though what I have received is package for the loaner tour, the package does look pretty much like what you would expect from a custom IEM. You will get an otterbox-like hard case, earwax cleaner, rubber band, detachable cable, the earpieces and good quality single and double flanges eartips of various sizes.

The stock cable is similar to Westone cable, which is decent and durable though nothing particularly fancy. The eartips are quite excellent in quality. The earpieces themselves are well built and actually quite small in size. The wooden faceplate is gorgeous. The nozzle of the earpiece that holds the eartips in place is what I’ll call ‘pig nose’ - as it seems to be just like a custom IEM’s nozzle that has been flatten out by hand, instead of molded to have ridge and socket like an universal IEM’s nozzle. It isn’t too big of a deal as it still holds the eartips in place fairly firmly and they never come off by their own.

Overall the build quality is excellent for something that is essentially hand built. Yes, they are not as precise as machined parts - but given their semi-custom nature, I think they are well acceptable.

Sound Quality 

Given these IEM are loaner, I didn’t carry out my usual 50 hours burn-in. But that shouldn’t be too much of an issue since balanced armature tends to benefit minimally from burn-in.

The sound signature of 3.Ai is warm, rich and laidback. Bass carries a good sense of fullness, if not a tab slow and fluid which resembles dynamic driver rather than BA. It reaches down fairly deep with good impact, and by not mean huge in quantity.

But because of having a richer and weightier tone, bass hit tends to sound bigger than it actually is, and more fun no less. Mid is slightly blend on the lower end, neither sweet nor lacking detail. On the upper end

however, there is an obvious dip and peak that makes it sounds a tiny bit off and grainy, like having a little itch on the back of the throat that you can’t get to. Treble extends well, but leaning toward the smoother side. It only misses the edge of sparkle and doesn’t actual sound dull, though analytical listener probably won’t find it enough. Soundstage is only fair, mostly because the warm and fullness of the presentation tend to get into the way of having a clean and clear separation and positioning. The biggest weakness of 3.Ai is however on the dip and peak in the upper mid. The dip reduces textural detail while peak gives it a rougher edge even though the IEM doesn’t sound sibilant.

The 4.Ai carries the same kind of warm and richness as the 3.Ai, but fuller and more forward. Bass runs decently deep and not as big or impactful as 3.Ai. It has the same rich and fullness in tone, but quantitatively closer to be just a notch more than neutral. Lower mid is much like the 3.Ai – decent, but nothing spectacular. The upper mid however behaves much better - fuller, though still not sweet, but definitely not grainy any more. Low treble is mostly smooth while higher treble has a bit of roll off, missing a fair amount of the top sparkles and crispiness. Soundstage is fair as well, for mostly the same reasons as 3.Ai. In a way, the 4.Ai is the mature version of 3.Ai. It is calmer and smoother on one hand, but not quite as fun on the other. It addresses the biggest weakness of the 3.Ai, which is the big dip and peak, but never quite brings it to the next level. The overall warm and neutral tone with the smooth treble actually makes the 4.Ai closer to a stage monitor sound, but it would have been better with a sweeter vocal and a touch more brightness. All and all, the 4.Ai is a notch better than 3.Ai.

Magnus 1 Cable

The Magnus 1 cable is Heir Audio’s own upgrade over the standard, Westone’ish cable. As mentioned, the standard version is actually quite good on its own. The Magnus 1 however, is even better in build quality. Despite being quad braided, with a slightly larger pins connector and a Neutrik right-angle 3.5mm plug, the cable doesn’t feel bulky at all. The cable is still soft and flexible, and seems more durable overall. It makes for quite a good alternative to the stock cable if you even need to replace it. I don’t find it a must-have for either the 3.Ai or 4.Ai and you certainly are not missing any of the Heir experience with just the stock cable alone.

Heir Audio: Incredible Service!

Hi Nina;


The IEM’s look beautiful and the way the whole package has been put together, personalized, and photographed is terrific. Normally when ordering something, as a client, I would just get some automated email saying the order has been shipped. But to get a full set of photos like this, and the request for confirmation, is incredible service. Thank you so much!


 A new proud owner of Heir Audio 8.A


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