PSB M4U 8 headphones review: Very fine noise-cancelling Bluetooth headphones
Superb sound and top-notch active noise cancellation make these wireless cans hard to beat.
By Scott Wilkinson
At a Glance
Superb Bluetooth sound quality
Excellent build quality
Controls are laid out well and easy to operate by feel
ANC causes slightly bloated bass
Somewhat anemic sound when unpowered
These stunning Bluetooth headphones offer superb sound and highly effective active noise cancellation.
Paul Barton, founder and chief designer of PSB Speakers, has a well-deserved reputation for creating many superb speakers over the last four decades. When he turned his attention to headphones in 2011, the result was the critically acclaimed M4U 2 over-ear model with active noise cancellation (ANC). Since then, PSB has introduced several iterations of this product: the M4U 1 (passive, no ANC), M4U 4 (wired in-ear monitors), M4U TW1 (Bluetooth in-ear monitors), and now the M4U 8 Bluetooth over-ear headphones.
Let’s find out if this newest model upholds the impressive legacy of PSB headphones.
The M4U 8 is a circumaural (over-ear) headphone with an adjustable, leatherette-clad headband and “gyro-suspended” earpads that conform to a wide variety of head sizes and form a nice seal around the ears. In fact, the inner sides of each earpad angle away from the opening to provide extra room for the pinna (outer ear). A total weight of 12.8 ounces is a bit heavier than other direct competitors, but I didn’t find it unduly weighty in any way. In fact, it bespeaks a high level of build quality, which I greatly appreciate.
The backs of the earcups are closed, and the dynamic mylar diaphragm measures 40 mm in diameter. Frequency response is specified from 20Hz to 20kHz (±1.5 dB).
Like many headphones these days, the M4U 8 is wireless, using Bluetooth 4.2 as the primary input. It supports the aptX HD profile, which provides up to 24-bit digital audio, and NFC (Near-Field Communication) pairing lets you pair the headphones with a compatible source device simply by touching them together. You can also connect a source to the M4U 8 with an analog cable—which can be plugged into the 3.5mm jack on either earcup—or a USB cable that also charges the internal batteries if the source device provides USB power. The M4U 8 comes with both types of cables that PSB claims are “tangle free.”
Speaking of the batteries, they consist of two rechargeable AAAs in the left earcup. You can easily replace them; you can even use non-rechargeable AAA batteries in a pinch. They take about four hours to fully charge using a wall-outlet USB adaptor, and they provide an average of 15 hours of operation.
Aside from powering the Bluetooth functionality, the batteries also power the onboard DAC (digital-to-analog converter), amplifier, and active noise cancellation (ANC). This function uses four microphones in the headphones to sample ambient sounds that are phase-inverted and mixed with the original to reduce their level by means of phase cancellation. When the onboard power amp is active (with or without ANC), pushing a button engages Transparency Mode, which temporarily drops the audio by 30dB and amplifies ambient sounds so you can hear the outside world.
One important feature is PSB’s RoomFeel technology, which is engaged when the power amp is active with or without ANC. Based on research performed by PSB and Harman, RoomFeel simulates the sonic signature of high-end speakers in a good listening room, which tends to emphasize lower frequencies because of omnidirectional reflections and roll off higher frequencies because they are more directional with fewer reflections. According to the M4U 8 datasheet, RoomFeel will “Take away the room and the music sounds limited to the space between your ears with an unnatural emphasis to the treble. RoomFeel opens up the soundstage while adding natural warmth to the sound.” We shall see.
The M4U 8’s four microphones are also used to answer calls on your mobile phone. If you receive a call while listening, hit a button, and the music pauses while you answer the call. Once you’re done, hit the button again to resume playback.
Unlike some wireless headphones, the M4U 8 still act as passive cans if the batteries are drained or you wish to conserve them by keeping the power off. In that case, you must connect an analog cable to the source, and there is no ANC, Bluetooth, or RoomFeel. Still, I heartily welcome this feature for those times when the batteries are dead and there’s no AC outlet to charge them.
The controls are found on the back of the right earcup. Starting at the top, the illuminated Bluetooth-pairing button flashes red and blue when waiting to pair with a source device. If your source device offers NFC pairing, simply enable NFC and Bluetooth in the device, place it against the front of the right earcup, and accept the pairing on the device when prompted.
Next is the volume up/down rocker, which does exactly what you’d expect: increase and decrease the volume from the source device. You can also press straight down on the rocker to engage Transparency Mode; press it again to disengage Transparency Mode.
Below the volume rocker is a 3-position slider switch that turns the battery power off and on in the lower and middle positions, respectively. Moving the slider to the upper position engages active noise cancellation.
Near the bottom of the earcup is a rocker that controls playback from the source device. Pushing the rocker straight down starts and pauses playback, while rocking it upward skips to the next track, and rocking it downward skips to the previous track. If you receive a phone call while listening, press the button straight down to pause the music and answer the phone; press it again to hang up and resume playback. You can also hold this button for five seconds to activate Siri or Google Assistant in the source device.
A mini-USB port at the bottom of the right earcup is used for charging the batteries and conveying audio from a computer (using the headphone’s DAC rather than the computer’s). Also at the bottom of each earcup is a 3.5mm, 2-channel, analog-audio input; you can plug a cable into either one, which is a nice touch. The support structure for each earcup has a gap that accommodates the cable.
The controls and connections are thoughtfully laid out. I especially appreciate that the main controls are well separated, which makes them very easy to find by feel. By contrast, some of the controls on the JBL Everest 710GA I recently reviewed run together, making them harder to find by feel. Also, I prefer physical controls over the newer touch-sensitive controls found on some other models.
Pairing the M4U 8 to my iPhone 6 went without a hitch. I started listening to Bach’s Toccata and Fugue in D minor as performed by the Canadian Brass (a world-renowned brass quintet) on The Essential Canadian Brass. The sound was beautiful, with each instrument clearly and accurately rendered. The tuba was rich and sonorous, the trumpets bright and clear. I could even hear the players taking breaths.
Next up was “The Journey Begins” from the score for the movie White Squall, by Jeff Rona. I play sea-shell trumpets on that selection in the score, which also includes synthesizers, Indonesian gamelan instruments, and ethnic flutes. The sea-shell trumpets were positively haunting, the low synth sounds were nice and deep, and the gamelan instruments were full of clearly defined high harmonics.
“Thunder and Blazes” (aka “Entrance of the Gladiators”) is a well-known circus march. I listened to the performance on the album Screamers by the Eastman Wind Ensemble under the direction of Frederick Fennell. All instrumental sections were well delineated, with excellent reproduction of all frequency ranges from the tubas and bass drum to the piccolos.
Turning to pop music, I listened to “The Nightfly” from Donald Fagen’s album of the same name. Fagen’s voice was faithfully rendered with background vocals spread across the soundstage. The electric bass was nice and full, with crisp drums and rich guitar solo front and center.
One of my favorite groups is Bela Fleck and the Flecktones. I listened to “Frontiers” from the group’s eponymous first album, which includes banjo, harmonica, acoustic piano, synths, jaw harp, electric bass, and synth drums. Once again, the rendition was superb, with deep but tuneful low bass, sharp drums, and well-defined harmonica.
To test the RoomFeel feature of the M4U 8, I compared the sound of “Frontiers” via Bluetooth and a 3.5mm analog-audio cable with the headphone power off. With the cable, the sound was somewhat veiled, and the drums seemed recessed in the background. Switching to Bluetooth, the sound was more open and expansive with greater richness and clarity.
I also performed the same comparison with “Every Breaking Wave” from U2’s Songs of Innocence. This is a bass-heavy track with a clean, full sound via Bluetooth. Using the cable with the power off, the sound was more veiled, and the bass was less well defined.
I have one minor concern here: The analog-audio cable that comes with the M4U 8 fits in the gap within the support structure for the earcups, but another such cable I had lying around did not. Its plug is too big to fit, so I had to make sure the earcup was angled to avoid the gap, reducing the effectiveness of the gyro suspension. That gap should be a bit larger to accommodate larger plugs.
In addition, I compared the performance with ANC on and off as I listened to “Trouble in Mind” from my wife Joanna Cazden’s album Living Through History. On that track, I play the solo trombone and synthesized sax-section backgrounds. With ANC enabled, the bass became somewhat bloated. After disengaging ANC, the sound settled down, becoming nice and clean with excellent balance between the instruments. Cazden’s vocals and my trombone were both rendered faithfully, as were the acoustic piano and bass.
When I first had a demo of the M4U 8 at CES last January, I was quite surprised at the effectiveness of ANC in PSB’s hotel suite. I had hoped to try it on a commercial flight, but I didn’t have that opportunity during this review. I did, however, wear the headphone while driving around my neighborhood. (I know, that’s illegal, but I only drove along side streets, and only for a short while.)
The ANC function was remarkably effective, greatly reducing the level of ambient noise. Listening to music, I still heard somewhat bloated bass, but that’s a small price to pay for such effective noise cancellation.
I asked Paul Barton about the difference in sound with ANC on and off. He said that he voiced the sound to measure almost identically with ANC on or off, but with less background noise, the brain perceives a bit more bass. In that case, I would have voiced the ANC sound to measure a bit lower in the bass to compensate for this perceptual effect.
My wife called my cell while I was listening at home. Answering the call worked exactly as expected—the ringtone played in the headphones, and I “picked up” by pressing the skip forward/back rocker straight down. My wife’s voice was perfectly clear, and she reported that mine was as well.
I’m deeply impressed with the PSB M4U 8. The Bluetooth sound quality is superb, and the ANC is exceptional, among the best I’ve ever heard. My only issue here is that the sound quality isn’t quite as good with ANC engaged, though I doubt anyone will hear much of a difference in a noisy environment such as an airplane.
In addition, the build quality is super-solid, the control layout is excellent, and it’s quite comfortable to wear even for extended listening sessions. I also appreciate the ability to act as a passive headphone if the batteries are dead, though in this case, the sound is a bit anemic, at least from my iPhone.
At $399, the M4U 8 is expensive. Among its direct competitors are the Bang & Olufsen Beoplay H9i ($345), Sony WH-1000XM3 ($348), Bose QuietComfort 35 II ($349), and B&W PX ($400). All are top-rated, so the one that’s best for you depends on your individual preferences. But if you’re in the market for high-end, noise-cancelling Bluetooth headphones, the PSB M4U 8 should be on your short list.