July 18, 2024
1 Solar System Way, Planet Earth, USA

64 Aspire 4 Audio Review

The people at 64 Audio have been dedicated to offering premium products and hi-fi quality. They have always aimed their IEMs at demanding audiophiles who expect luxurious facets in their equipment. This is why it's so amazing that they created an IEM designed for musicians, with an MSRP of $899. The flat response and high-fidelity price make the Aspire 4 an interesting IEM with plenty of competition. Brands like Campfire, Noble, Sennheiser and now FiiO (FA19 expected in July) all have great products for about the same price. Let's see how the new Aspire 4 compares to these and if they're worth checking out.

What is in the box

  • Case
  • Foam and silicone pads.
  • IPX cable
  • cleaning tool
  • 1/4″ adapter
  • shirt clip

64 Audio Aspire 4 Universal In-Ear Monitor in the Box

Look and feel: Aspire 4

The Aspire 4 is elegant and unnoticeable. People looking for a flashy IEM won't find the style they're looking for in this headset. In a stage context, I doubt this would affect anyone's performance and remain subtle while used. Personally, I love the minimalist style and black design. A simple silver 64 Audio logo on the body is the most obvious look, and I wish they went for a totally “killed” look. However, branding is important and it makes sense for the logo to stand out from the rest of the colors.

What I'm not crazy about is the fit of the IEM. 64 Audio opts for a metal body in most of their designs and the plastic on this unit is too light to stay secure in my ears. The cable is thin and light enough to be comfortable, but I'm concerned about its long-term durability. That being said, the cable did not pull out the seal as I moved around while listening. Simply put, my ears didn't like the ergonomic design. They put pressure on the antihelix of my ear and I never felt comfortable no matter which tip I tried.

It's good that 64 Audio includes so many tips. Of all of them, the medium or small foam ones were the only ones that sealed correctly. The rest continued to come out, reducing the bass and treble in the listening environment. However, mileage may vary considering we all have unique ear shapes.

Design – Aspira 4

The Aspire 4 has 4 separate controllers as the name suggests. Here there are 1 dynamic driver for the bass, 2 BA drivers in the midrange and another BA driver for the treble. Listeners can expect a “flat and brighter-leaning” sound signature. A frequency response of 20 Hz to 18 kHz means that audiophiles without hearing loss may lose some lightness in the treble range. At the same time, this is considered on a case-by-case basis and many older listeners will not have perfect hearing beyond 18 kHz. On stage, this can be beneficial considering that unwanted feedback will not be heard as loudly on these monitors. At 104 dB at 1 kHz at 1 mw these will be easily handled. I was able to use my laptop's 3.5mm output and the Apple dongle just fine while listening. Users who connect to a good wireless beltpack should have no problem handling them.

What disappoints me is the use of the 64 Audio 45° IPX cable. Although other companies like Universal Ears offer IPX compatible IEMs, they do not offer the same angled case. For this reason, I'm not sure how interchangeable these cables can be without affecting the feel. I think this is an attempt to improve the ergonomics of the design. On the other hand, breaking a cable means you have to replace it with another 64 Audio angled cable. Good luck finding an analog upgrade if you plan to change the finishes. In addition to this, IPX connections are not as available as their MMCX or 2-pin counterparts. This sounds like an obstacle waiting to happen for any touring musician who needs backup equipment.

Soundstage – Aspire 4

The most exciting thing about this IEM lies in the staging. The imaging accuracy is some of the best I've heard in a headphone and it's clear that 64 Audio designed this aspect with professionals in mind. I wouldn't say the staging is either near or far, but this is not the place for that. Monitoring depends more on the precision of the sound images than on the width or height, which is more of an audiophile characteristic. Sounds recorded on an omnidirectional microphone have almost no bleed between the right and left signals. I heard some height and width, but it's medium in its soundstage. The tracking of reverbs and delays is very clear and precise.

Specifically because of the staging, I think the Aspire 4 would work phenomenally as a luxury gaming IEM, as well as a monitoring tool. People who play competitively will have a noticeable advantage in listening to opponents sneak up on them. You will be able to identify exactly where the sounds are coming from on the map, as well as part of their distance.

Listening Impressions – Aspire 4


The Aspire 4's bass will be strong enough to give listeners and professionals great accuracy. As for the sub-bass, this IEM is too flat to offer a palpable sensation in this frequency range. I never heard the bass really extend enough to make me feel it. Instruments in the midrange that still have harmonics in the high bass feel warm and round. With this in mind, I felt that there was so much sonic competition with the treble range, that bass instruments sounded weak. Sometimes I was left wanting more warmth in sounds that had a fragile character. This could be good for musicians who prefer a warm sound and want their monitors to sit clearly in their mix.

Hermeto Pasqual's “Bebe” is mixed with a warm and punchy upright bass line that doubles with the piano part. Listening to the Aspire 4 again, I got a good character from the instruments, but the sound never felt as tangible as it normally does. The guitars on this track also had so much definition that it seemed as if the harmonic complexity of the solo was being taken away from them. When I wanted a resonant timbre, all I got was string noise. There's something missing in the bass that I think a slight boost would bring it closer to a truly flat level.


I had the biggest complaints with the midrange of this IEM. The biggest criticism I have occurs specifically in the upper mids. The tuning of the BA drivers is not synchronized enough to avoid volume drops with large harmonic jumps. There's a noticeable volume shift on tracks like 200 Stab Wounds' “Ride the Flatline,” where Ray MacDonald goes from heavy riffs to sliding Floyd-Rose solos with elite precision. The driver drops dramatically at certain points in the upper treble range, as if surgical frequency tuning has been performed. When I think about reference response curves, I rarely think about surgically tuned media. For $899, I think any IEM should be able to handle dramatic tone changes, ESPECIALLY a flat one designed for musicians.

At the same time, I believe that music focused on vocal direction will not suffer from this drawback. The Aspire 4's lower mids can have a warm, fuzzy sound. There is great clarity and depth due to the low mid and treble frequencies. At the same time, all musicians use angular playing at times to achieve the quality they expect in their music. Everyone from Jim Hall to Kerry King to Art Tatum uses octave jumps and this IEM doesn't give me the fullness of the music's harmony.


Of all the aspects of the frequency response, I was most impressed by the treble. Although it is a flat IEM, I feel that the best tuning comes from the upper register. The sounds are still sharp and clear but do not reach the point of becoming sibilant and tiring. I could listen to this IEM for hours and had no problems continuing. There is some reduction at certain points in the treble, but these drops are not as dramatic as in the midrange.

What I noticed about the treble on this IEM was that it brought great clarity to almost all instruments and made feedback sounds fit comfortably into a mix. On the contrary, the combination of supplemented highs and surgical mids creates a thinness in the sounds. I understand that the trade-off for providing greater clarity is often less warmth. It's welcome in certain settings like The Grateful Dead, where both Jerry Garcia and Bobby Weir set their EQs high. The thinness here and on the steel guitar remains intact and the character of these instruments is not complemented.


The Aspire 4 is a serious professional tool that comes with a serious price tag. For all the things it does well, improvements could be made to beef up the sound. The volume dropout typically associated with BA armature drivers occurs here. Add this to the fact that cables for this unit will not be as available as the MMCX or 2-pin options. At the same time, certain aspects such as soundstage and crystal clarity make this a suitable tool for performers, audio professionals and gamers. Will audiophiles be impressed with the sound at this price? That depends on your personal preferences, but I still think listeners should wait for the second generation of this model.

Get the 64 Audio Vacuum 4 and much more in Audio 46.

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