Sony IER-M7 Review: A Taste of Something Greater

Introduction

In 2018, Sony updated their flagship line of in-ear monitors with the release of the IER-M7, M9, and Z1R. The M9 gained almost unanimous praise as an excellent IEM best suited as a stage monitor. The Z1R was a little more controversial with its exorbitant price tag, antagonistic fit, and uncompromising sound. For the few that could make it work, the Z1R seemed to be endgame. But today I want to talk about the overlooked, youngest brother of the line-up, the IER-M7. 

On the surface, the M7 looks very similar to the M9. It has almost exactly the same shell design and boasts four of Sony's in-house balanced armatures instead of five. It also comes with the same extremely generous set of accessories: 13 pairs of Sony tips, two cables, and a hard carrying case. The cable isn't exactly the prettiest but it does the job splendidly with little cable noise and no cable memory whatsoever. Fit, comfort, and isolation was equally great for me. You can tell that these IEMs were truly made for stage use.

The biggest difference between them is the fact that the M7 shells are made out of a light plastic while the M9 is crafted from magnesium. Well that and the carbon fiber faceplate on the M9. Truth be told, when I had the chance to hold them side by side, I can't help but be disappointed that Sony sacrificed that slice of premium on the M7. Maybe there's was an actual engineering decision here but at an MSRP of $500 I would expect something a little more substantial.

Sound

Though the M7 is marketed as a "stage" or "studio" IEM, I didn't find it sterile or boring. It has an overall warm neutral tuning that's on the bassy side with laid back vocals. It plays nicely with the vast majority of music I threw at it. However, I was able to hear the difference in driver engagement during different parts of a track where the crossovers get employed. Sony's BAs seem to have a distinct sound to them and the transitions aren't always seemless. Alone, the mid drivers have a sense of clarity that really jumps out at you until the bass drivers kick in to add their own flavor to complete the M7's sound. Interestingly enough, when I demo'd the M7 next to the M9 a year ago, I found the M7 to be borderline dark. But listening to it again for this review, I didn't have that impression at all. While not the ideal tuning for me, it's plenty enjoyable.

Bass 

The low end BAs are probably the most interesting drivers in the M7 (and M9). For those who don't know, Sony's BAs are designed completely differently from others in the industry and have a unique firing mechanism. I don't know the exact details but suffice it to say it can clearly be heard in the bass of the M7. If you didn't know it was a BA, it could almost pass for a dynamic driver. I'd say it's about 70% of the way to a good DD and preferable to a lot of bad ones. There's a decent amount of rumble in the subbass and the M7 leans towards being boomy rather than punchy which is uncharacteristic of BA IEMs. Fortunately, the clarity in the midbass isn't too negatively affected and the BA speed is mostly still there. Overall, the bass is elevated and bleeds into the mids. My nitpick with the bass is that it needs more of a defined leading edge. Right now, the notes in the bass sound rounded off which makes it a little soft and contributes to the boominess. It can also get a little muddy at times when there's too much going on due to a relative lack of definition. Of course, the better the recording/mastering, the better the M7 will perform.

Mids

The mids of the M7 are warm and laid back. Those that enjoy a lusher tone that's less forward will likely enjoy the M7's tuning. Personally, I'd prefer more upper mids to drive the energy of vocals and electric guitars. For acoustic instruments, the balance in the mids has a very clear, welcoming tone that performs excellently in unplugged-type setlists. As mentioned previously, on its own, the mid BAs have an engaging quality to it. But when the track goes from a mid-focused acoustic passage to bringing in booming drums, there is a sense of disconnect as the bass BAs kick in and dilutes the singular clarity of the mids. The laid back nature of the upper mids means vocals are never harsh or fatiguing to listen to, nor is there any issue with sibilance. I think the M7 does a good job in toeing the line between being too relaxed and having just enough vocal presence to prevent it from sounding buried.

Highs

The treble of the M7 definitely takes a backseat in the overall sound signature. It dips quite rapidly starting at the lower treble which partially mutes the attack of the hats and cymbals. Treble is present but kept to a minimum to avoid listener fatigue. That said, I didn't feel like it was overly dark and thought that there was a surprising amount of treble extension and presence where it mattered. I was actually pretty surprised looking at the graphs after listening as I didn't expect that large of a scoop past the upper mids. Personally, I would have liked just a bit more presence in the treble to bring forth the shine from the hats/cymbals and give the upper harmonics of vocals more breathing space. Overall, I thought the treble of the M7 was tastefully done for what they were going for. The timbre isn't perfect but there are no glaring weaknesses here.

Presentation

The biggest highlight for me was the soundstage and imaging. The M7 has large soundstage that feels natural to me and solid imaging ability to go along with it. The relaxed upper mids does lend to the illusion of a more open space though I wish there was a bit more treble to give clarity and balance out the occasional muddiness from the bass. Instrument separation is quite decent for the most part and resolution is a clear step up from the <$200 class of IEMs, as expected. 

The presentation of the M7 works pretty well for me. Its stage, resolution, and tonal balance comes together well enough in a way that's enjoyable and easy to listen to but it isn't always a seamless experience. I can't shake the feeling that the M7 is the glued together pieces of something greater. That the M7 is a sort of first draft of an idealized entity. Of course, I'm being facetious here. That something is the M9 and the sound quality improvement is fairly striking if you ever have the chance to hear them side by side.

Should You Buy It?

At its MSRP of $500, it's a bit of a tough pill to swallow for me personally. On one hand, I quite enjoyed my time with the M7 and I found myself reaching for them again and again for this review even though I had other IEMs in line for ear time. But on the other hand, Sony's choice to seemingly cheap out on the build quality irks me (though kudos for the plentiful accessory set) and the M7's "almost there but not quite" feeling does stick in the back of my mind. This is exacerbated by the "mid-fi desert" as I like to call it, where IEMs at this price range have to fight cheaper mid-fi IEMs like the Moondrop Blessing 2 in that ever present price/performance arms race or against used entry level hi-fi IEMs. It's a tough spot to be in especially when new entrants to the scene like the DUNU SA6 shake up the already select few mid-fi models. I don't think I can fully recommend the Sony IER-M7 at its asking price. But if you ever manage to find a used one in good condition for about $250-300 or cheaper, I'd say its compromises are palatable and sound quality thoroughly enjoyable. It'll serve as a nice stopgap until you make the plunge into endgame.

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