Reviewed on: SoundStage! Solo, June 2022

I measured the AXS Audio Professional Earbuds using laboratory-grade equipment: a GRAS Model 43AG ear/cheek simulator with KB5000/KB5001 simulated pinnae, and an Audiomatica Clio 12 QC audio analyzer. (To save space in the chart legends, I’ll refer to the earphones in the charts by the model number, e.g., “AXSE01.”) For isolation measurements, I used a laptop computer running TrueRTA software with an M-Audio MobilePre USB audio interface. I used a MEE Audio Connect Bluetooth transmitter to get signals into the earphones. I used the supplied large silicone tips for all measurements because they fit best in the ear simulator. These are “flat” measurements; no diffuse-field or free-field compensation curve was employed. Note that I’m unable to do spectral-decay measurements on most true wireless earphones due to the latency. If you’d like to learn more about what our measurements mean, click here.

Frequency response

This chart shows the Professional Earbuds’ frequency response. This looks pretty standard for a product like this, although the peak in the 3kHz region is a couple dB higher than we might normally see, which corresponds precisely with what I heard. (BTW, I had already finished writing the review when I did these measurements, and my Clio analyzer can’t read, so it couldn’t have been influenced by my opinions.) I also tried taking these measurements with the volume on the earphones set at four different levels, ranging from maximum to -29dB, to see how much difference in response there was at different volume levels, but the frequency response did not change significantly—it was up only about 1dB in the bass at the two lower settings.

Frequency response

This chart shows how the Professional Earbuds’ tonal balance changes when they’re in Voice Through, ANC on, and ANC off modes. This is impressive—there’s effectively no difference.

Frequency response

This chart shows the Professional Earbuds’ right-channel response compared with various earphones, including the KEF Mu3s, which of all the true wireless earphones I’ve measured, are the ones that come closest to the Harman curve. You can see that the Professional Earbuds have a narrow, higher lower-treble peak in the 3kHz range, and they also have the excess upper bass I recently complained about in my monthly column—but this time, I didn’t notice the bass bloat, probably because the lower-treble peak counteracted it.


Distortion in the Professional Earbuds is very low, even at the extremely loud level of 100dBA (measured with pink noise). That’s impressive, because some true wireless earphones can’t even reach 100dBA.


In this chart, the external noise level is 85dB SPL, and numbers below that indicate the degree of attenuation of outside sounds. The lower the lines, the better the isolation. With all the earphones whose isolation is shown here, the measurement was taken with the noise canceling on. The Professional Earbuds’ noise canceling isn’t a standout, but it’s enough to provide a much more pleasant listening experience when you’re flying.


This chart shows the effect of the Voice Through mode, and how good the passive isolation of the Professional Earbuds is. These are both typical responses.


Latency, measured with the MEE Audio Connect transmitter (which is equipped with aptX and aptX Low Latency), ran consistently in the range of 235ms. This isn’t what I’d call low-latency operation, but it’s not bad, because many true wireless models run over 300ms.

Bottom line: Other than the subtle frequency-response anomalies pointed out above, I’d consider the engineering of the Professional Earbuds better-than-average for true wireless earphones.

. . . Brent Butterworth