Recommended Reference ComponentWe began our list of Recommended Reference Components five years ago, in September 2010. Since then, 60 products have been added to the list, but only one earphone model: Etymotic Research’s ER-4PTs, which S. Andrea Sundaram reviewed for SoundStage! Xperience in October 2011. This month, we’re adding PSB’s M4U 4 in-ear ’phones, which Brent Butterworth reviewed for Xperience last month.

The PSB M4U 4s were created by well-known, award-winning loudspeaker designer Paul Barton, who engineered into them some characteristics of his speakers, in the form of what PSB calls RoomFeel. In his review, Brent described RoomFeel as “a frequency-response curve intended to create a sound more like that of real speakers in a real room.”

PSB M4U 4 earphones

Barton also designed NAD’s Viso HP20 in-ear headphones, but this is his first two-way design. Each M4U 4 earpiece contains a moving-coil dynamic driver for the lower frequencies and a balanced-armature driver for the highs, the various frequencies managed by a tiny crossover in each earpiece.

Like PSB’s highly regarded M4U 2 and M4U 1 headphones, the M4U 4s come with detachable cables and numerous accessories, as Brent described:

The M4U 4s come with six sets of eartips: three of silicone and three of Comply foam, each material in three sizes. (Paul Barton voiced the earphones using the Comply tips.) Also included are: 1.4m cables, one with an Apple-compatible inline mike and remote control, one without; an 1/8”-to-1/4” adapter; a dual-mono airplane adapter; and a zippered travel case.

PSB M4U 4 earphones

While the accessories help make the M4U 4s easier and more convenient to travel with, it was the sound that Brent found special:

But while the M4U 4s didn’t have as much mid- and upper bass as I’m used to, I kept coming back to them because their mids and treble were so great, and because their portrayal of spaciousness sounded so right. I could really appreciate this with recordings such as “Cultural Treason,” from the terrific Primal Scream, by David Chesky’s group Jazz in the New Harmonic (16/44.1 WAV, Chesky JD 369). In this purist recording, everything was recorded in a large, ambient space with a simple microphone array and a minimum of postprocessing. I’ve attended a couple of Chesky’s recording sessions, and the M4U 4s made his work sound as it’s supposed to. Peter Washington’s double bass dominated my right ear, as if it were about 6’ away. Chesky’s acoustic piano was in my left ear, sounding as if about 15’ away, and Javon Jackson’s tenor sax and Jeremy Pelt’s trumpet were roughly centered about 20’ back, so that they wouldn’t dominate the mix and could take better advantage of the ambience of the venue. The bass level seemed just right -- the unamplified double bass sounded like an unamplified double bass.

The M4U 4s also got the balance right with music that relies more on the lower range of bass to get its groove on. A perfect example is “Leaving Los Feliz,” from Mark Ronson’s hyper-popular Uptown Special (256kbps MP3, RCA). I can’t tell if it’s a synth or a bass guitar providing the bottom end on this tune, but to my ears, the M4U 4s provided plenty of groove without obscuring the voices, guitar, and drums. In fact, I could perceive Ronson’s carefully layered mix to a greater degree than I have listening through speakers or relatively inexpensive headphones -- especially Kevin Parker’s voice, which sounded huge yet still focused enough to salvage some degree of humanity. The M4U 4’s precise, uncolored mids and treble made this track a real pleasure to hear; over and over, I kept clicking back to the beginning to listen again. I wonder, though, if what I heard matched Ronson’s intent. I gotta think he’d want more bottom end, to get his listeners’ butts moving more.

Brent concluded:

The PSBs’ mids and treble are so uncolored, and their bass so precise, that I have to think that the M4U 4s will be the go-to earphones for me.

PSB M4U 4 earphone

Had that been Brent’s final word on the M4U 4s, it would have been enough for us to include Paul Barton’s newest earphones in our Recommended Reference Components list. When we followed up with Brent shortly after the review was published, to see if he had any further thoughts about the M4U 4s, he had this to say:

The M4U 4s may be a little bass-shy, but following the review, I’ve gotten a little more used to that. I still find that the midrange and treble sound so smooth and natural that I’ve decided to use them as my reference for under-$500 earphone sound quality.

Perhaps they’ll become your reference, too.

Manufacturer contact information:

PSB Speakers
633 Granite Court
Pickering, Ontario L1W 3K1
Phone: (905) 831-6555
Fax: (905) 837-6357