The wireless headphone category grows more crowded by the day and to only pay attention to the big brands like Apple, Sony, and Bose is a very large mistake.
Having previously reviewed the AONIC 50, I was curious to test out the newer AONIC 40, which promises better noise cancellation and longer battery life for $50 less. Is it too good to be true or a “Shure” thing?
Out of the gate, the $249 AONIC 40 is up for quite a challenge as the AONIC 50 has become a personal favorite and earned its place atop our Best Wireless Headphones of 2021.
Build Quality
The construction is similar with both having headbands wrapped in protein leather and memory foam. Both have aluminum hinges and gimbals, and both sport impact resistant polymer cups with the AONIC 40 being slightly smaller with its 40mm driver.
What differentiates the AONIC 40 is the folding hinges that allows it to fold for travel; and the 40mm driver (vs 50mm), and differing/simplified controls. Internally, LDAC and Bluetooth aptX LL (low latency) are not supported on the AONIC 40 so those wanting LDAC connectivity will want to stick with the AONIC 50. The 40 does offer aptX HD and AAC support covering most Apple, and Android devices, and most DAPs. See all specifications compared here.
Usability
While the controls are simplified, they are not made more ergonomic, and although I applaud the use of physical buttons instead of touch sensors, the fact that users have little in the way of tactile clues (one raised dot on the play button) to differentiate functions is not a plus. Most will likely choose to use the app instead because it is easier to navigate.
AONIC 40 users have the option of using the AONIC 40 wirelessly via aptX, aptX HD, AAC, or SBC protocols, or using it via USB where the AONIC 40 operates as a USB DAC/amp in addition to being a headphone, and finally via the 3.5mm analog cable that allows the user to connect an external source and use the headphone with it powered off.
To use the headphone as a USB connected device, it does have to be powered on but will charge the device simultaneously; you can listen and charge at the same time.
When first powered on, the AONIC 40 goes into pairing mode and it remembers previous pairings. To pair a new device with the AONIC 40 off, press and hold the power button until you hear the Bluetooth pairing mode prompt (about 6 seconds).
The AONIC 40 also supports Bluetooth multipoint so can be paired to two source devices at the same time; the process is very much the same as for a single device, connect the first device, turn it off, and then connect the second.
When the first device is powered back on, it will re-establish the connection and both devices are now paired and connected. I had no issues with pairing to an iPhone, Android, Windows PC, and iPad in my testing.
Once paired, I found connections to be very stable with break ups only occurring if solid barriers were introduced or distances ranged more than 15 meters or more.
When connected via USB, the AONIC 40 draws power from its host and I found that it worked well with PCs and the Android devices I had on hand, but when using my new iPhone, I received a “this accessory requires too much power” prompt.
I received the same prompt using the iPhone 12/13 with the camera kit and DD HiFi MFi06F Lightning to USB Type-A Female USB OTG Cable.
The battery life is exceptional and the advertised 25 hour life is accurate with every option turned on and volume at unrealistic levels. I had no difficulty at all getting 30+ hours out the AONIC 40 with ANC enabled (at roughly the mid-point) and volume at normal listening levels.
Using Bluetooth multipoint or ANC at maximum setting does drain the battery a bit faster but still gave the rated life. Shure advertises that 15 minutes of charge can give up to 5 hours of listening time and while I found it somewhat dependent on the charger used, the specified charge rate is not inaccurate.
One of the big things touted by Shure is the re-worked ANC which now exists in the digital domain instead of the analog version found in the AONIC 50. This move allows for more complete noise removal with less artifacts and veiling according to Shure.
When I reviewed the AONIC 50, I found its ANC performance to be near the top of the class but like most, it worked best for low frequency droning noises and struggled with sharper upper frequency noise.
Passive isolation on the AONIC 40 is quite good with an average reduction in sound volume between 6 and 10 dB depending on frequency so the ambient feature is useful when situational awareness is required.
ANC
I found the ambient mode to be improved over the earlier model in that conversations cut through more cleanly; the ANC performed at the same level as the previous generation which makes it one of the best, but I had hoped for some degree of improvement.
The ANC even adjusted to its most potent setting is still best with planes, trains, and vacuum noises, and while it reduces voices somewhat, don’t expect complete removal.
Traffic noise like horns, sirens, and whistlers are lowered a few decibels and are less invasive, but still present. When A/B testing with ANC on/off, there is little or no change in overall signature which is a plus. Similarly, with ambient mode, there is very little difference in signature when enabled.
Far too often, enabling ANC introduces a veil or low level hiss to the signature but that is not the case with the AONIC 40.
The mics are excellent at picking up ambient noise and helping filter out sounds in ANC mode, but the phone call quality was not as impressive. I found that wind noise was quite audible to callers on the other end of the call, and people could hear environmental noise when I was speaking.
The Sony WH-1000XM4 and Bose 700 are much better options if you use your headphones all day to take phone calls.
Sound
Putting aside my issues with the call quality and some of its ANC performance, the Shure AONIC 40 delivers excellent sound quality.
While not perfectly linear, it comes closer to neutral than a lot of its competitors and when combined with above average dynamics and resolution, it makes the AONIC 40 one of the best sounding options anywhere near its price.
There is a sub-bass emphasis that gives the AONIC 40 solid low-end impact but it also keeps the sub-bass from being perfectly clean so there is some texture to the sub-bass but not the clarity that is evident through the rest of the frequency range.
The mid bass drops back from its early emphasis and has good detail and even micro-detail. There is defined impact where it is needed but with the drivers quick attack and short sustain, it doesn’t linger and thicken the sound.
The lower midrange is quite clean and there is very little bleed from the upper bass which only adds to the clarity of the sound.
Male vocals have good tonality and weight, but not quite as much presence in the mix as their female counterparts which step forward due to an upper midrange push.
The best way to show off the midrange capabilities of the AONIC 40 is piano and acoustic guitar where each note has good detail from the initial attack through the sustain and decay. Guitar growl has a nice sharp edge and rasp as well. The tonality of the violin and other string instruments is very accurate and I find classical music very pleasing.
Higher vocals do stand forward in the mix due to the upper midrange, lower treble push and can be a hint too far forward. This is particularly evident on tracks that emphasize the vocals to begin with, and sometimes it can become too much of a good thing. Thankfully, the EQ in the app gives the user the option to reduce that slightly and neutralize that extra energy that can become a bit nasal and shouty; I’m increasingly convinced that it is not the AONIC 40 causing the issue but the recordings that I’ve been listening to.
The lower treble shares the lift of the upper midrange and has good energy for percussion with cymbals having a nice realistic tone. The treble has good extension with roll-off somewhere above 14kHz and enough top end to keep from feeling claustrophobic.
With the Shure AONIC 40 being a closed back, one would expect the soundstage to be somewhat limited in its width and depth and I found that to be only partially true.
It is definitely wider than deeper sounding and there is a surprising amount of height as well. The layering and imaging are very good; instruments are well separated and carved rather firmly into place.
Conclusion
Should you buy the Shure AONIC 40?
That answer might be somewhat divisive depending on what’s really important to you when it comes to selecting a wireless ANC headphone.
If you prioritize sound quality and battery life — you might not find a better deal below $250.
If you are more concerned with build quality, call quality, ergonomics, and comfort — the Sony and Bose alternatives for almost $100 more will be a better option.
Does that additional $100 (or more) get you better sound quality or battery life?
It does not.
The Shure AONIC 40 might be the best value in wireless ANC headphones right now.
Where to buy: Was $250. Now $199 at Amazon »
