System Room Den/Office

Fritz Carbon 7

Woo WA5 300B Headphone Amplifier

Oppo BDP 105, IMAC 27 inch with Audirvana and Amarra software for itunes

Sennheiser HD800, Hifiman HE6, Fostex TH900, PSB M4U, Ultimate Ears UE18, Hifiman RB600

Nordost Blue Heaven Power Cords, Nordost Blue Heaven Interconnect cables, Nordost Blue Heaven Speaker cables/banana terminated, Nordost Blue Heaven USB cable, Audioquest Diamondback interconnect, Audioquest Black Mamba.


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Positive Feedback ISSUE 70
november/december 2013



M4U2 Headphones

as reviewed by Frank Iacone


psb m4u2 headphones

In 1997 I owned the PSB Stratus Gold loudspeakers designed by Paul Barton, and I fell in love with the sound signature and musicality that PSB products offered. PSB has a storied history in speaker design, and Paul Barton is a revolutionary designer who knows how to voice his products with great transparency and accuracy to the musical truth. When I heard he had designed a noise-canceling headphone, I was very excited and wanted to get hold of a pair for review. The PSB sound was evident when I first put them on; I was transported back to 1997 and a very familiar sound. The sound of PSB is so inviting, and immediately reminded me of the Stratus Gold Speakers. The M4U2 has the Paul Barton stamp of sound in its signature. Warm and inviting with exceptional transparency and musicality are a few of the traits of the M4U2. The PSB exceptional sound signature is very evident.


The M4U2 is a noise-canceling headphone with a built in amplifier running on AA batteries and a life expectancy of 55 hours. The circum-aural over the ear design has a frequency response of 20Hz-20Hz and can provide full range bass. The design can also be used in passive mode if you desire to not use the amplifier. If the batteries die you can still use the M4U2 without interruption in passive mode without any interruption in musical enjoyment. The isolation is listed at -10dB offering reasonable isolation of noise that might interrupt the listening session. The fully closed design allows for privacy and will not disturb others while you're listening to music. The leatherette ear pads are two-way adjustable gyro-suspended for optimal ergonomics and supreme comfort, according to PSB. The heavy polycarbonate headband is also adjustable. The headphones can be folded down to carry in the supplied hard case. The detachable cable has a 1/8 termination for portable devices, but also includes a 1/4 inch adapter for use with desktop and other full size amplification. The headphone cable termination also allows the user to use both the left and right cup for termination to make it easier to hook up to an amplifier or portable device. Weight is 362 grams with the batteries installed.

psb m4u2 headphones

Listening Equipment and Music Choices

Music used for this review included sources from the 27 inch iMac lossless files playing with either Audirvana or Amara software, integrated with iTunes. Also used were two portable source players, the iPod touch, and the iBasso DX50 portable DAP player. System sources also included the excellent Oppo BDP 105, the Woo WA5 tube amplifier, and a GSX MK11 solid-state amplifier designed by Headamp . Music used included a wide variety of pop and jazz, along with a good mixture of classical and folk recordings. Both female and male vocals were used during the three-month audition of these headphones.


When I first started listening to the M4U2 headphone I was brought back in time to my fond recollection of PSB speakers, the sound was easily identifiable with Paul Barton. Paul has been designing speakers for over 40 years and the sound signature is very distinctive. PSB transducers are voiced with a warmer sound than many products on the market. The M4U2 has the similar signature to all PSB products, it has transparency with terrific balance; the bass is very extended and deep, but also has inner detail. The treble is extended but never harsh or grainy.

Listening to the Klaus Ignatzek Group Day for Night album really showcased the detail the M4U2 was capable of reproducing. On the "Beautiful Colors" track I could hear the inner detail of the piano. The sound stage was excellent for a closed headphone, possessing a wide stage with nice front to rear depth. The saxophone was easily identifiable in the rear of the stage with the bass guitar in the center rear. I could hear the bass notes very clearly and they were well defined with texture. The midrange was outstanding on this track. The soothing track allowed me to disappear into the music. The sound was very distinctive with musicality and tone. The instruments had realistic color, while the tone of the saxophone and piano possessed the accuracy I hear in live performances.

"Ring of Time" from Argento's Valentino Dances on Reference Recordings is a terrific track to listen for treble extension. The "Ring of Time" piece was commissioned by the Minnesota Orchestra in 1972 to celebrate its 70th anniversary. Argento wrote the piece for large orchestration with quadruple woodwinds and a very large percussion unit. The piece also was written so that the music would reveal the passage of time; the seasons of the year, and the times of the day from dawn to midnight. The three-percussionists use wind chimes and other bell tones in a very complex arrangement and the M4U2 nailed the performance. I could hear the layer of musicians in the recording along with a crystal clear liquid treble that made the music so exciting. The layering on the M4U2 is excellent for complex classical recordings. I did not feel like I was missing anything in the performance. Each section was vivid and the overall music was deeply involving. The treble showed no weak signs in reproducing this very complex piece. Many other headphones simply collapse when trying to reproduce this demanding track, and the M4U2 sailed through it with musicality and let me become totally involved with the music. The M4U2 delivered a breathtaking and exciting performance with this outstanding recording.

Heather Massey's Lock My Heart album, recorded with Dick Hyman playing the piano, is another outstanding recording. Heather's voice is sexy and very seductive. The piano session on this recording is also magical where the synergy with Heather and Dick Hyman is clearly evident. Using the main system, with the Woo WA5 and the Oppo BDP 105, the performance of the M4U2 was scaled way up. It became more musical and the sound stage expanded beyond what I experienced with the iBasso DX50. The M4U2 really came to life on the track "Bewitched, Bothered and Bewildered." Heather's vocal was so articulate, and Dick Hymans piano was so real and alive, it was if they were here playing the performance just for me. I became so involved in the performance that I completely forgot about the M4U2. The headphones disappeared as the inner detail of Hymans piano played with such vivid transparency, and Heather sang so seductively… it was as if I could reach out and touch her. Simply breathtaking. The synergy between Massey and Hyman was something to really behold.

Nat King Cole's the Very Thought of You with Gordon Jenkins is an excellent SACD recording mastered by Steve Hoffman. Nat's soothing voice was very apparent and articulate on "Very Thought of You." I could clearly hear the entire vocal with articulation and transparency. The orchestration was vivid, realistic, and sounded excellent. The layering of the musicians across the hall, and Nat's voice coming from the center, completely relaxed me. The detail of the performance was all there… nothing was excluded. I was simply lost in the music. The M4U2 let me hear everything the recording had to offer with terrific transparency. The detail from this headphone is remarkable, let alone at the cost of $399.

Terrance Blanchard's excellent Let's Get Love is another terrific album. The SACD has some outstanding female vocalists with Terrance playing his trumpet with some great jazz session players. Diana Krall singing the title track "Let's Get Lost" sounded excellent. Blanchard's trumpet playing is all there. The bass guitar was coming from the center rear of the stage with Blanchard to the left, and the drummer to the rear. The M4U2 had good separation of individual instruments with focus and detail and just the right amount space and air. Once again, I was astonished at how good the sound stage was from a closed headphone and one especially in the price range of the M4U2.

Jane Monheit, on the same album, singing "Too Young to Go Steady" really shone on the M4U2. The piano playing by Edward Simon was outstanding, as was Monheit's very seductive voice. Derrick Nievergelt's acoustic bass was detailed and extended; as was Blanchard's haunting trumpet solo. The drum work by Eric Harlan sounded so alive, with the cymbals shimmering and never splashy. They had an extended tone to them, much like you would hear live. Monheit's voice, and the outstanding performance of the musicians, made this a memorable track. I could hear everything the recording had to offer. Again the performance was involving, and the M4U2 totally evaporated leaving me with nothing but the music.

The Civil Wars second album really showcases the duo's vocals as well as outstanding songwriting. Joy Williams and John Paul White make terrific music together. The M4U2 did not disappoint in the performance of this outstanding album. Joy's vocal is featured on the track "The One that Got Away". The M4U2 let me hear everything on this track. "From The Valley" is another excellent track that has Joy's vocal featured with great background vocals by John Paul White. The synergy on this track with the duo is clearly evident. John Paul White's vocal is exceptionally clear and vivid and the synergy between the duo is easily heard with the M4U2. The separation and timing on the recording is excellent. I had my toes tapping to this spiritual tune, and felt like they were taking me to the valley and not from the valley. I was there with them and the music just kept flowing as I felt Jesus carrying me away. I get chills every time I listen to this track; it grips my soul and again the m4U2 let me feel all the passion and the music consumed me.

Joshua Redman's Freedom in the Groove is jazz at its finest. Using both the GSX MK11 and the Burson Conductor SL with the M4U2 proved quite musical. The M4U2 felt right at home with these two solid-state amplifiers. Both amps were very synergistic and dynamic in feeding the PSB headphone. The GSX Mk11 and the Conductor SL are both very transparent amplifiers that just get out of the way. The M4U2 playing "When the Sun Comes Down" had plenty of air around Redman's saxophone. The bass was very extended, and the sound stage was equally wide. The music just flowed with deep bass extension. The musicality was clearly evident via both of these outstanding amplifiers.

psb m4u2 headphones

Active Mode and Noise Cancellation

Using the M4U2 active mode was a revelation with the iPod touch. The iPod clearly benefitted from the amplifier built into the M4U2. It added more dynamics and transparency to the tracks I used with the iPod touch, and could play to levels louder than I could ever listen to. The noise-cancelling feature is excellent. I could hear no outside noise coming through the phones. With the internal amplifier, the listening sessions always rewarded me with musicality, good inner detail, and transparency. It added to the listening pleasure.

Using the iBasso DX50 the results were similar. I had the same sense of added dynamic and transparency as I had heard with the iPod. The iBasso also has its own built in amplifier in the digital player, but the M4U2 amplifier still managed to step up the player by adding more authority and musicality to the tunes. I enjoyed using the active mode when listening to my portable devices. The feature lets you have amplification without the necessity of carrying a portable amplifier around with you and is available with the flip of a switch on the headphone.


Paul Barton has designed another winner with the M4U2. It never failed to impress me. The bass is fully extended and the treble extension is also excellent. Musicality is my preference when listening to either a headphone or a speaker, and the PSB M4U2 delivered all the things I admire most in a product. The tonality of the instruments and the transparency coming from the vocalists, with air and separation from instruments, was first rate. The M4U2 is a first class portable $399 headphone that will satisfy most music lovers with hours of enjoyable music presentation.

The M4U2 can basically go anywhere with you and provide hours of musical enjoyment at a very high level. The only bone I could pick with this headphone is that headband is stiff, and it is a little heavy for a portable use. I am really nitpicking here because despite the heavy weight, the M4U2 delivers all the things I love in a headphone.

The balanced and neutral presentation combined with musicality, all in a product priced so reasonably, is exceptional. The M4U2 simply let me get lost in the music; it was so very involving I forgot I was listening to a headphone and just enjoyed the many hours I spent listening. Paul Barton has succeeded in bringing the famous PSB sound to a portable solution of the highest caliber. Highly recommended for anyone needing a headphone, for either portable usage or for when you want to drown out the entire world around you and get lost with your music. The PSB M4U2 is one of my favorite portable solutions and is highly recommended. Frank Iacone

 M4U2 Headphones
Retail: $399.95