Headphone Review: Heir Audio 4.Ai

[IMG]Heir Audio | In-Ear Monitors | $ 399.00

Heir Audio is a new growing company. I first heard their entry-level 3.Ai about 2 months ago. They impressed me quite a bit exposing the fun side of audio in a strong, technical fashion. Their 4.Ai model is one step up from the 3.Ai and aims to represent a more neutral sound; in contrast to the 3.Ai, it does this well. 

In the Box

  • Heir Audio 4.Ai
  • Carrying Case
  • Silicone Tips (Blue-Barred Hybrid Single Flange: S/M/L; Red Hybrid Single Flange: S/M/L; Dual Flanged: S/M/L)
  • IEM Cleaning Tool
[IMG]Inlcuded with the 4.Ai is the same accessory set included with the 3.Ai.


The 4.Ai I received have a same beautiful wooden finish the 3.Ai had. The amboyna burl gives off a beautiful texture that glares gleefully in the light. The external housing itself uses a smooth acrylic that is clear to reveal the textured wooden faceplate on one end. However, on the other, it shows off a beautiful dark, almost black color. The housings are beautiful crafted with attention to detail.

The design of the 4.Ai look downright gorgeous.



Powering the 4.Ai, as the name suggests, are 4 balanced armature drivers. 2 bass drivers, 1 midrange driver, and 1 tweeter deliver the smooth tunes straight into your ears through the dual-bored system. The 4.Ai offer a relaxingly smooth signature that has an enjoyable warmth to it.

Two bores separate out the bass tones from the rest before entering your ear canal.


This is the most dominant part of the audio spectrum for the 4.Ai. The 4s offer a nice strong body to the entire bass that adds a nice presence for it throughout the tunes. The low bass can hit hard with a thorough impact while not giving up on speed and maintaining a nice punch. Sub-bass extension begins rolling off a little earlier than I’d like, but doesn’t take away from deep-bass texturing. The texturing has a solid feel to it, but is strong and rendered well.
Bass: ★★★★½


The midrange of the 4.Ai has a nice smoothness associated with it. The lower-mids detail retrieval is the strong point being able to represent guitars in a scenic, lively way. As we go up, we find lush, smooth vocals that have a beautiful warm touch behind them. They, however, do lack sweetness which takes quite a bit away from the vocal energy vocalists have. Midrange clarity is rendered decently by the 4.Ai. It does a fine job at it, but certainly isn’t the best.
Mids: ★★★★½


Going up higher, we find that the treble has a focus on the upper highs. The result is a strong, convincing splash that holds a strong presence and very good separation despite a slightly early roll off. If we go down however, we find the lower-highs really lacking in energy, extension. Presence of this area is OK, the snare snaps can be heard, but don’t really snap down the way they should. Overall though, the highs do have a well-characterized delicacy behind them.
Highs: ★★★★½

Audio: ★★★★½


The Heir Audio 4.Ai are each hand-built with attention to detail. Included to protect this detail is a nice hard-case. Heir shipped my model with their portable case that works for on-the-go use if you have a purse or bag. It still isn’t too pocket friendly, but protects like an OtterBox would.

A strong case bears the Heir Audio logo.

The housings are made of the same acrylic that houses Heir’s custom IEMs. This material is strong and can be shaped appropriately with a full seal around the entire housing. The craftsmanship is beautiful on the 4.Ais and have a beautiful sense of quality to it. The housings don’t use a recessed connector to connect the cable. Instead, the cable sticks out a little further than it should since it doesn’t sit flush with the housing.

The housings are crafted gorgeously, the cable connection doesn’t seem as perfectly crafted.

The cable that comes with the 4.Ai is the same cable that is included with the 3.Ai and Aurisoncis ASG series. The cable is twisted and feels great. It’s flexible and rarely tangles. Furthermore, the cable feels strong and is also replaceable if it were to ever go bad. No one likes spending 400 bucks on a cable repair when it should be 50.

The cable included on the 4.Ai is strong.

The headphone jack on this cable is larger. The housing around the jack is very thick and strong while the strain relief coming out is strong, yet flexible. The jack itself has gold plating that ensures that it will last a little longer.

The headphone jack is built very well.



The housings on the Heir Audio 4.Ai is a lot smaller than the pictures show. Actually, this housing is smaller than the 3.Ai housing. The acrylic is smooth and fits very naturally inside the ear and the lightweight properties of the IEM allow you to wear it for hours. Heir Audio includes a nice set of tips to allow users to fit the IEM appropriately.

Nine sets of tips are included to ensure a proper fit.



The Heir Audio 4.Ai are priced at a competitive 399 dollars. At this price, they do offer a value for what you get. However, there are IEMs that offer similar sound quality at a lower price. Heir Audio’s 4.Ai do offer enough for the money you spend on them. The warm sound signature with great comfort and beautiful design bring it all together and add value to the package you get with the 4s.

A removeable cable is included. It can turn a 400 dollar replacement into a more-affordable 50 dollar repair.


Final Thoughts

Heir Audio once again brings such a beautiful IEM to the table. Crafted with the same love that goes into all their customs, the 4.Ai offers an entirely inoffensive sound signature that anyone is sure to like. The IEM looks beautiful and even has a few customization options available.

I’d like to thank Brennan for the product loan.

Overall Score
† All prices are in US currency.
This review was written by the iFans.com Review Team. Cumulative scores are rounded to the nearest half or full star.
This accessory, product, or app was received as a sample. Thanks Brennan for the product sample.
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