Edit: I bought a Schiit Magni 2 just to see how it sounded with clean amping and the sound has greatly improved. The Asgard, though I love how it sounds with my other headphones, isn't the best match for the Vibro. It needs a clean signal for it to shine.
 
Zach’s blog on his fascination with wood, its properties and how it can be utilized by man is a good read.I recommend you all to check it out. The man uses the resource on his products in a way that blends both aesthetics and sound in the best way imaginable. This, of course, goes beyond the Vibro – check out the Blackwood and Omni models and how picturesque they are. Due to the use of wood, each pair is unique – which lends a sense of ownership that indiscernible factory designs from other manufacturers can’t reproduce.

I was introduced to ZMF headphones by a friend of mine who had just recently purchased a Fostex THX-00 from Massdrop. He was absolutely in love with the sound but was looking for something to complement his repertoire of headphones. He fully recognized the V/W shaped sound of the THX-00 and wanted something more neutral. However, he didn’t want to lose the bass impact that the Fostex gave him at the same time. After looking around, he showed me the ZMF website and told me about how it’s a small-scale business run by some guy named Zach Mehrbach. I’ll admit, I didn’t quite grasp how the idea of tonewood (something I was familiar with as I have two acoustic guitars on hand specifically for their different wood and the sound difference) could translate to headphones. I thought the designs looked neat though, especially the Omni cups.

My friend soon got himself a pair of Blackwood Omnis, the top of the line offering by ZMF. It seemed he had finally found what he was looking for, neutrality without the cost of “fun.” I had owned a neutral pair of headphones once, recently sold, in the form of the Sennheiser HD600. I enjoyed it for vocals, but the bass wasn’t to my liking. I had looked into Planar Magnetics and managed to find an excellent deal on a new Hifiman HE400i due to a friend visiting Beijing over the winter. It quickly became my favourite pair and motivated me to sell both my HD600 and Beyerdynamic DT990 as I felt it blended and superseded what I enjoyed about both cans. With a little spare cash, I set out to see for myself what the ZMF hype was about.

I went for the Vibros because I wanted to experience what a truly “fun” headphone would sound like without attempting to be anything but that – at no cost of mids. I’m not bass-head, but I wanted bass. I read that further up the line, ZMF headphones tended to be a bit more laid back and I wanted none of that. Also my budget could only allow for a Vibro so hey I’ll happily take what I can. I’m glad I took the plunge, but I won’t be getting rid of my HE400i and this is why:

The Vibro is warm, very warm. “Dark” is a word that has been used to describe it and I don’t disagree. The Mk. 2 is described to extend the treble, but I haven’t heard one so I cannot say. Before I analyze what I hear and like about the Vibro Mk. 1, I will plainly state that if you only listen to certain genres of music like pop, rap and EDM – this should be your go-to set of cans at this price point. However, if you’re like me and listen to a vast array of music – you want another pair to round off your collection that can handle the genres and recordings that the Vibro has difficulty with.

Consider an aggressive genre like metal. Now consider an aggressive metal band like Slayer. When you listen to Slayer, you want all cylinders to be firing on whatever audio system you have. You wouldn’t enjoy it as much if something fell short. I’m glad to say that the Vibro doesn’t fall short in this regard. The cherry cups and planar magnetic drivers combine to give sheer power to whatever you are listening to. This is not a laid-back set of headphones at all. It pushes the music out at you in a bombastic manner that makes you take notice of everything you hear – and most of the time you can hear it all clearly.

If you have a song you really like but can’t stand how sibilant it can sound at times, this is the pair of headphones for you. If you have an album you wish had a bit more kick to it, these are the headphones you should listen to it with. If you want to kick back and listen to some progressive rock, these probably aren’t the headphones for you – which is why I’ll be keeping my HE400i. The treble roll-off on the Vibro is reliant on what you’re listening to – both recording wise and genre wise. For pop and rap, it isn’t even noticeable 90% of the time. For soft rock, it’s quite noticeable and can feel a bit stifling – particularly with the likes of Pink Floyd. If you enjoy listening to vinyl rips, unless they are super clear and equalized, you might not enjoy them on this. EQ itself is something I tend to not use very much but I would recommend it to listeners who find the treble roll-off to be a bit too much. I, personally, will just switch headphones whenever I’m in the mood for genres this isn’t the best for.

However, if you’re listening to something that fits well with the Vibro’s sound signature then there isn’t anything like it in this price range. You’ll find yourself switching the bass ports depending on your mood and genre you’re listening to – but keep a close eye on where you put the little rubber plugs because it’s very easy to misplace them. I personally have two plugs in most of the time, with only one plug in for pop/rap and no plugs in for electronic music.

I have to give a shoutout to Zach for his work with his headphones on behalf of myself and my friend who owns the Omni. I would absolutely recommend peering into his product line to anyone looking to get into “fun” high end audio. This isn’t the realm of the HD800 and its benefits. This is the realm of musically-tuned drivers encased in sexy wood that is uncompromising in its identity and market niche.

The Procurement Process:
 
Being a student and all, I could barely afford a fresh pair of Vibros straight from the factory. Plus, my impatient ass didn't want to sit around waiting for a 2-3 week shipment. As luck should have it, a fellow "carouseller" (an ebay clone created locally for Singapore) advertised an almost mint condition ZMF Vibro (specifically the Massdrop Galaxy Edition Purple) at approximately 360 USD. Without hesitation, I sold most of my current headphones/iems (Beyerdynamic Custom One Pros, Noble 4+ Silver Dragon Cables) to fund this purchase. Fostex Mods are hard to come by in Singapore and having little to no experience with planar-magnetics, I decided to pick up these little curiosities.
 
 
 
General Information:
 
ZMF (an abbreviation for Zach Mehrbach Films), is a side project opened by a guitar manufacturer, Zach Mehrbach. Fond of music and pursuing the craft of good audio, he decided to use his work experience with wood and its resonant properties to create "Franken-headphones", utilizing modular parts (padded headbands, lambskin earpads, different cable terminations, tunable open-bass ports). The consumers can opt for different terminations, wood type + finish, earpads and headbands etc. His wife also offers the service of handcrafting various cable upgrades that can be purchased alongside the headphones themselves. Zach often frequents various threads on Head-fi, interacting with the general crowd on the forums.
 
From the looks of it, this is much more than a passion project. 
 
This particular model is circum-aural, utilizing the infamous Fostex T50RP drivers with added damping, a completely new sound signature and CNC'ed Cherry Wood Earcups that supposedly improve the dynamic response of the headphones. They're also fitted with Pilot Headbands and Lambskin earpads. They come with a standard 1/4 inch jack terminated cable, with Audeze style connectors (mini xlr's). Their rated impedance is at 50 ohms.
 
 
 
Initial Impressions:
 
The first thing that I noticed was the size of the entire package. The non-descript white cardboard box (with a ZMF sticker) was rather wide. Lifting up the front lid of the box, I was greeted by a pair of chunky beasts. The headphones are fitted with ZMF's famous Pilot Headband and Earpads made out of Lambskin. Most of its size comes from the solid padding for extra comfort. 
 
Out of the box, the package includes the headphones themselves, more than sufficient bubblewrap, a satin carrying case (don't know why you'd want to carry these gargantuan headphones out) and a certificate of authenticity (complete with serialized numbers and the date of manufacture). I would've expected a Pelican hard-shell case if I paid full price for them. Considering I purchased these at a significant discount, I sure as hell can't complain.
 
The Purple Cherrywood Earcups are reminiscent of exotic furniture from luxury brands. They have a similar alluring charm that draws people to its distinct appearance. A few blemishes and an imperfect surface make them look more natural and less artificial than a crapty piece of machined chipboard. Replacing the plastic earcups was a brilliant idea that stood out from similarly priced competition (MrSpeakers, Mayflower Electronics). 
 
The heavily-padded headband (Pilot Headbands) and the 2-3 inch thick Lambskin Earpads adds a needed comfort for long listening sessions. The headband effectively balances the weight of the entire headphone across the skull effectively. They clamp with just enough force to provide a snug fit on the head. Understandably, Planar-magnetic headphones are often heavy and outlandishly big. Don't get me wrong, these are WAY larger than your run-of-the-mill pair of headphones. These are cantankerous and some would be put off by its "not so subtle" profile. I am happy to report that the weight does not affect its listening comfort. I wear them for over 4 hours (gaming+ music sessions) on a daily basis, free from ear-fatigue or a sore head (from the clamping force). From my 2-3 months of using these headphones, I can easily vouch for their comfort. 
 
With regards to the build quality, I'll let this "durability test" video speak for itself.
 
https://www.youtube.com/watch?v=odQUqnOKGl8 
 
 
 
Sound Quality:
 
Setup used: Aune X1S + ZMF Vibro Mkii + Foobar 2000 v1.3.6
 
Smooth and intimate, the natural sound of the Vibro Mkii is bound to attract an audience. They sound lush and intimate, with a "front row" sound-stage that immerses you in the music's forefront. Instrument separation is substantial enough without sounding incoherent. They especially shine on jazz recordings or female vocal tracks. Diana Krall's California Dreamin was an exercise in perfection. Her smokey voice, the glint from the violin section and a tightly strung bass almost sounded like a live recreation of that specific track.
 
Most importantly, the purchase of this modified pair of Fostex T50RP (retailing at approximately 180 USD) is definitely justified. Sounding unlike its little brother, the Vibro's are slightly mellower, with a cloudy sound that exercises control on the treble and sibilant high frequencies that can cause excessive ear fatigue. Do not be fooled by my previous statement. The Vibros have more than sufficient detail without the dry harshness commonly associated with crystalline highs and realistic treble. They pump out an assertive bass section, with incredible mid-bass speeds and just enough sub-bass for those who prefer a leaner low-end. Do take note that these headphones aren't for bassheads looking out for sub-woofer levels of crazy. The mid-bass decay is too fast and rigid to be called a basshead's dream. 
 
Alas, there is so much one can do to push headphone drivers. The Fostex T50RP drivers has a tendency to lack ultra-low frequencies. This was noticeable on the ZMF Vibros, with a strange lack of sub-bass decay and natural slam. To be fair, these drivers have their limits and there's only so much one can mod. 
 
For customization and all its intended purposes, the headphones has 3 tunable ports on each earcup. Rubber stoppers can be inserted into these ports to close and open the sound. In my honest opinion, this only affects the sound-stage significantly, with minor differences to the bass and treble regions. The summaries are as written below.
 
No Ports Closed => Semi-open Sound-Stage, Lush Bass Section, Slightly Masked Treble
One Port Closed => Less open Sound-Stage (compared to previous configuration), More Control on the Bass, More Treble Detail
Two Ports Closed => Less open Sound-Stage (compared to previous configuration), Bass becomes more intimate, Treble is alittle more Brittle
Three Ports Closed => Closed but more forward Sound-Stage (compared to previous configuration), Bass is more "in your face", Treble gains slightly more detail
 
 
 
All ends well
 
Even with its few caveats, the ZMF Vibros are easily the most engaging and musical pair of planars to ever come by. These are purposefully made to be as inviting as possible. Even at full price, these headphones are definitely comparable to the likes of higher end planar magnetic headphones (Audeze EL-8, Hifiman HE400i etc.) If they were paired with a reference amplifier/dac section with ample juice, these headphones will definitely shine and show its vast potential. Here is a poorly done shot of my pair (I suck at picture taking, my apologies):

 
Pros: Comfort, build quality, sub-bass quality, multiple sound tunings.
Cons: Shouty upper mids
Tonal Balance: Warm to balanced depending on ports.
Style: Closed over-ear
Listening Set-Up: Musicbee (FLAC) -> Matrix HPA-3U
Cost: Starting at $499
 

Reviewing Process

I’ve had the Vibro for about a month and during the time I’ve used them to skype, play League of Legends and to listen to a wide assortment of music. During my time with them I feel that I’ve become comfortable enough with their sound and build to comment on them fairly. With that said reviews never trump experience and I encourage readers to demo products before buying them when possible.
 
Thanks Zach at ZMF for letting me review these!
 

Build & Fit

 
Build
The Vibro are a highly modified Fostex T50rp mod, so much so that they’re barely recognizable as the T50rp outside of the headband and the adjustment sliders. Zach has reworked the aesthetics in collaboration partly with Luke over at Vibro Labs who makes the beautiful wooden cups for this line. The wooden cups are finished with care and precision, these being constructed of beautiful red walnut, with 3 bass ports that allow for the user to change the sound signature of the Vibro, but we’ll talk more about that later.
 
The Vibro features a choice of two straps, mine shipped with a leather strap that is thick, cleanly cut and secured soundly to the headband. The pads are new and now made of lambskin and they look as great as they feel. The last big change to the build is the removable cable, now a dual XLR instead of the single locking 3.5mm the T50rp once had. The connectors sit firmly attached to the headphone and the attached cable feels sturdily built.
 
Based on this pair I feel safe to say that Zach has put a lot of time and care into modifying the looks of this while keeping the build quality up to par. Luke’s cups are beautifully crafted and they’re certainly a conversation starter when I have friends come over.
 
Fit
The Vibro are now shipped with angled lambskin pads that are super plush and super comfortable. The pads feel uniform in height and firmness as they form their seal around my ears. Clamp is moderate, not enough to headbang, but they won’t just fall off willy nilly. Downwards pressure is mild, though certainly noticed as the wooden cups and planar drivers add some heft to the headphone. The Vibro never disappear from my head, but I have worn these for 3 hours with no issues. Isolation is phenomenal though, noise stays in even when listening on the loud side with no bass ports closed.
 

Sound Quality

Preface: This portion of the review will be written from the perspective of having no bass ports closed. There will be a short write-up for the change in sound with the ports closed below.
 
TLR
With stock bass ports the Vibro are v-shaped headphone that packs a serious punch in the low-end. The sound is layered wonderfully with great imaging capabilities, a joy to listen to the likes of James Blake with while sounding competent for everything else I’ve listened to.
 
Bass
Using the bass shaker test at the Ultimate Headphone Test page the Vibro are capable of deep sub-bass response that sounds near linear, with a small dip before the mid bass, but nothing alarming.
 
In real world listening, soulful electronic music absolutely shines here; sounding incredible with James Blake’s self-titled debut as well as Jamie xx’s debut In Colour, for example. Both albums highlight the silky smooth sub-bass in presence, impact and speed. That isn’t to say that the sub-bass is super fast, but it is quick enough to keep up with James Blake’s Limit to Your Love. The sub-bass is thick, which creates a slightly sluggish sub-bass response, while offering a pleasant rumble that brings Jamie xx’s Sleep Sounds to life. The sub-bass isn’t the end-all be-all, it lacks control at times, but it sounds phenomenal for the dreamy bassy music of these two UK electronic stars.
 
The midbass is certainly prominent but less so than the sub-bass, with the bass sounding as if there were a mild downward slope from the sub-bass to the midbass. With that said the midbass is thick and syrupy with a bit of bloat into the midrange, powerful and punchy but overly present at times. Pop music sounds phenomenal with the added midbass thump, as does the variety of electronic music that I’ve tested. In-fact anything danceable benefits from the added umph in the midbass. The midbass is pushy and bloated though and the tunes of Steely Dan sound too thick in the lower-end at times and throw the song off balance.
 
Stock, the bass is tuned to be emphasized, adding thickness and impact. I find the tuning to excel with bass heavy tunes as well as dance hits, while sounding overly present otherwise.
 
Mids & Highs
The midrange is lush and thick in the lower regions, emphasizing and adding warmth to lower ranged vocals, acoustic piano and tom hits on acoustic drum kits. The lower midrange suffers from a bit of grain as well as midbass bleed, causing a sense of recession in the lower ranges while also masking detail in this range. The midrange leans natural sounding though, even if a bit syrupy, reminding me a bit of a thicker HD600. Clarity and detail are sacrificed for warmth and thickness, which falls in line with my preference of bass heavy electronic music with the Vibro.
 
The uppermids become a bit shouty, noticeably in upper vocal ranges as well as the snare drum. The shouty vocals are most apparent with female vocals, though Pink Matter by Fank Ocean sounds overly forward at times as do some other more powerful male singers. The higher frequencies are tamed and done rather well though, sounding smooth and balanced while having a hint of sparkle throughout.
 
Presentation
The soundstage is intimate while having a good sense of stereo imaging, layering and depth. Instrument separation is decent, but held back by the thick lower end which takes up a large portion of the soundstage at times. The Vibro are closed headphones and certainly sound it in how they present the sound, not as closed as something like the M50, but certainly no K701.
 
Bass Port Options
Preface
Since it’s a bit difficult to go back and forth in a timely manner due to the nature of inserting and removing the stoppers I can not easily go back and forth between tunings. The thoughts expressed here are done by memory and could be a consequence of expectation bias. I am sharing these thoughts in good faith though and hope they are helpful.
 
One Port Closed
Stock I felt that the bass was overly assertive and undercontrolled, fun for certain genres, but too prominent enjoy more nuanced tunes with. With one port closed the bass significantly tightens up without sacrificing the powerful response that the stock tuning offers. If stock is a dark club with pulsating dance tunes, one port closed is a smokey jazz club with single malt scotch being poured generously. This tuning is smooth and sexy from head to toe, warm while lively, musical while nuanced.
 
With the bass tightened up the midrange and soundstage sound significantly more coherent. The midrange is still lush, but sounds cleaner and more detailed with a more natural tone throughout. In turn the soundstage also sounds cleaner with instrument separation benefitting heavily from the lack of low-end bloat. Listening to Lana Del Rey has never sounded as good and I keep wanting to reach for a cigar when a Steely Dan tune comes on, I’m in love.
 
Two Ports Closed
This tuning sounds really well balanced while maintaining a hint of warmth that the Vibro is known for. The uppermids are still a bit shouty, which will likely be common through all tunings, but I don’t find it overly forward. This tuning further solidifies my love for this headphone, adding further versatility to this headphone and solidifying it as a definite recommendation from me.
 
Three Ports Closed
At first I felt that this tuning was too mid forward and lean in the lows, but after giving my ears time to adjust I now feel that this tuning is the most balanced and natural of the four. By plugging up the last open port the soundstage sounds the most accurate and spacious of the bunch, while also sounding the cleanest from a sound reproduction stance. This tuning nears neutral to my ears and is quite versatile in genre compatibility. From 1970s Japanese fusion jazz to 2000s electrodisco this tuning is very capable.
 

Conclusion

The Vibro are the first new headphone in quite a while that have left an impression on me. I am astonished at the beautiful aesthetics, the sturdy build quality and the versatility of the sound signatures. All in all the Vibro are the total package for someone looking for a closed headphone within the $500 price range and they receive a full recommendation from me.

Introduction
 
Hello everyone, it sure has been awhile. I've had these headphones for a little over a week and a half now after a five week wait (which was not Zach's fault...I'll elaborate on that later,) so I now feel I have a non-hyped, unbiased view of these headphones I can share with you safely without falling into the unfortunate spiral of hype train nonsense that the Alpha Prime subjected me to.
I'm not going to spoil the fun here, so no intro-TL;DR. Also, I'm going to include the Blackwood impressions and the reason I'm not going to do the Blackwood review until late April-Early May in the comments.
 
Build, Appearances, and Comfort
 
I'll start out with the pictures of the Vibro, Blackwood, and my Maine Coon kitten.
 
The first thing you'll notice is the thing that sets the ZMF headphones apart from the rest of the Fostex mods: he uses wooden cups to improve what he can do with the driver. The Vibro uses a cherry wood cup that can be customized with just about any stain you want. As with most things like this, my iPhone can't do justice to how well these cups were made and stained. The sliders can likewise be customized to a variety of colors so that you can match your cup with the sliders. At the end of the cups, Zach installed two 3-pin mini-XLR connectors that can be used with just about any aftermarket cable for Audeze cans, which is quite convenient if you ever need to find a replacement.
 
As far as the cups' integrity goes, I don't think you'll ever have to worry about them cracking. They're pretty thick and sturdy, which will help out the soft cherry take abuse. Not that you should ever put these in that kind of situation. Despite this, however, the Vibro stays noticeably lighter than its Blackwood cousin.
The headband is the original Fostex one, so I'll just say that it is incredibly sturdy and flexible.
 
The ear pads may seem familiar to you, as they should. They're the MrSpeaker's Alpha Pads, which are incredibly comfy and very soft. My only issues with them have been the foam flattening as time goes on and the lamb leather being thinner than it should be. For the time being, however, this is the best and only choice available.
As far as the headband comfort is considered, you have two choices: the thick strap of leather known as the buffalo strap (a classic for planars) and a foam-filled (pleather?) pad known as the pilot pad. Which one is better? Honestly, it's all preference. However, if you have a head large enough to make the Audeze LCD 2 seem like a normal headphone, than you should probably go with the pilot pad, as it offers more room for your noggin.
 
Now, to be completely blunt, these are planars so expect them to be heavy. The Vibro isn't near as bad as, let's say, the LCD 2.2, but it's very similar to the HE400 in weight. The strap/pilot pad does distribute the weight and make it unnoticeable unless you have the bad habit of wearing headphones for more than eight hours a day like I do.
My only real issue with the build is the how the Alpha Pads are over the cup, which is a huge nitpicky-kind of thing. I would personally prefer to have the cups completely uncovered in all their glory, but I understand limitations make the near impossible.
 
As a side note that will be rendered obsolete in a couple months, the pilot pad seems a bit more fragile than I would have liked. The leather holding the foam is pleathery and seems like it would tear easily. But, like I said, that opinion will be obsolete soon.
 
The Sound
 
Now for the real reason you came here. If I could describe this headphone in two words, it would be "controlled chaos." Usually this would raise a red flag, as no headphone should have "chaos" in the description its sound unless it happens to describe what the hell the HE1000 is going to do to your wallet, but it is quite a good thing. With the exception of the normal Fostex 10khz spike, this headphone is very dark. Not the bad undetailed kind of dark, but the smooth, relaxing kind of high-end. It can be slower in its sound at times, and fast at others...it's truly bizarre, but that's the nature of a mid-forward headphone sometimes. Hell, if you want to skip right to the end, I can say "this does everything well, but does some things VERY exceptional" and call it day.
 
With one port open (which is my music-oriented preference,) the headphone is very warm and HE500-like with a more lush forwardness in the mids (much like the HE400i.) The bass and the mids are linear in an upward sense, with the subbass rolling off softly. It is a very enjoyable headphone for music, and does pretty well with just about anything that doesn't demand obscene amounts of detail or a glorious soundstage (as it is about the same size as the HE400i's...if not a touch smaller due to being a touch more forward.)
 
If you're feeling risky, go ahead and open another port. You'll be welcomed with a much more impactful sound that seems almost cinematic in quality (not the bad kind of cinematic) with just how "big" it is in a way. The Vibro becomes more bass leaning, with just a slight more emphasis in that area that keeps it more in line with how lush the mids are. In fact, the added bass helps in this area. While the one port open makes the headphone more musical and forward, two ports make it more organic. I could also just say you'll notice the bass is bigger, the rolloff is slightly worse, and the mids are a bit lusher. To make it even more simpler, the headphone has more body to it.
 
Now, if you open up ALL the ports like Zach intended...well, that's where the "organized chaos" comes into play. Simply put, the headphone can't decide what the hell it wants to do with itself in the best possible way. The bass is clearly the focal point, but the mids are having none of it and want to still be part of the action. You have a mid-forward headphone with a whole lot of bass all of a sudden, and it oddly works very very well with most popular genres (more modern rock, dubstep, hiphop, EDM, ect.) Maybe not so much for quieter, more subtle kinds of genres, but for everything else? This headphone simply rocks with all the ports open.
 
Now, you may be wondering why my preference for music is only one port open. Simply put, I'd rather have glorious mids as the focus and have it sound like the HE400i (and I was going to do a comparison here...but there's no point. It sounds incredibly similar to the HE400i until you start opening the bass ports.) But all the ports open does very well for things outside of music. Specifically, anything cinematic or gaming-related. Now, I'm not going to take credit for describing this as the best bass for gaming, as that honor goes to Mad Lust Envy, but this headphone has the dynamic-driver quality of having slow decaying, lingering, large-bodied bass. It hits you hard and keeps its fist going until it runs out of face and flies off. Most planars go deep very easily, but decay very quickly. So, while they will punch you very hard in the face in a way that almost explodes your face (like the LCD 2.2,) the Vibro keeps following it up in hopes that it can turn your head inside-out for ****s and giggles. In that way, this headphone does games like Skyrim, Battlefield, ect very well without losing much detail due to how forward the mids still are. Sure, you're not going to outdo that guy with a AD700 and treble boost, but at least you'll actually enjoying yourself as you feel the impact of the grenade launcher you fired in his face with only five-feet of clearance.
 
That said, the subbass is more noticeable in its rolloff. It goes deeper than most headphones dream of, but it isn't as much as other planars like the...well the Blackwood, LCD 2.2, HE560...you get the point. It oddly rolls off at the same point the HE500 does (but the mid-bass being emphasized on the Vibro makes it more apparent.)
 
To simplify how the plugs change the sound, here's a nice chart:
 
0 Ports Open: Sounds like a Grado without the super-treble and less air. Meaning, it's more like a hill signature.
 
1 Port Open: Sounds like a slightly more forward HE400i but darker. Bringing some Roman history in here, but it's very much like a subtle Aqueduct kind of a curve that drops off around the highs.
 
2 Ports Open: Sounds more bass emphasized, and the frequency seems to have a subtle downhill slope kind of signature. Best example I can think of is the TH600 but vastly better mids and less bright. Honestly, it makes the entire headphone much more lush.
 
3 Ports Open: You could try listening for some treble, but you won't hear anything over the sounds of your head being beaten viciously by the bass. The bass goes from controlled to slightly loose and looming, hitting very hard (but not deep) and decaying slowly.
 
If you don't like dark headphones, this won't do much for you. The highs are pretty smooth, but can sound a bit recessed sometimes. This headphone is obviously colored and fun, and I love it for that. It can be fatiguing at times, however, as it can become very aggressive at times. Very, very aggressive.
 
Light Comparisons with Headphones Around This Price Range
 
HE400i
 
With one port open, the Vibro sounds very much like the HE400i, but darker. Like I said, it would be a waste to elaborate more sound-wise, but here's some other things to consider:
The HE400i is lighter. The Vibro looks better and can be customized in appearance. However, it does take a couple weeks, where-as the HE400i may take a couple days depending on where you live and shipping. The HE400i is more open and the soundstage is slightly larger, but not by a significant margin. The Vibro uses mini-XLR, which is a lot more versitile and less annoying than screw-in adapters. Zach is much easier to deal with than a customer service center. The Vibro's sound can be customized...and for ~$70 more, can be tuned with Blackwood tuning, creating a headphone that has better technicalities but still has the warm sound of the Vibro.
 
The Alpha Dog
 
Both have bass ports, but the ZMF handles it much better. Where as the Alpha Dog can actually be harmed by using the bass port too much, the ZMF is as simple as putting in the little rubber things. However, those rubber plugs have a horrible tendency of falling out if they're even brushed on something, as they can't go all the way in like the Blackwood allows the plugs to go. They're both just as dark, but the Alpha Dog more goes for a reference sound and soundstage, while the Vibro is more aimed to be enjoyable and relaxing (even though it is a very aggressive headphone at times.) The Alpha Dog does have the added benefit of being able to be tuned in both dots AND bass, albeit one of them is more permanent than the other if used too much. Both are built well and sound good, but I prefer the wood over the plastic cups.
 
Conclusion
 
The xVibro is a very excellent, unique headphone. It is the sort of sound I would personally attribute to the "fun" kind of signature (bassy with good mids but dark,) but I'm also in the minority on that one. It sounds like a closed alternative of an open headphone, but then differentiates itself the more you open its bass ports. However, the bass does roll off slightly, and the rolloff does become more and more noticeable as the rest of the bass becomes larger and larger. It's not the end of the world, however, since it still goes deeper than a large majority of other headphones. Zach takes his time making sure these turn out perfectly, and it honestly shows.

Background
 
I bought the ZMF x Vibro after owning the HE-400 for about a year. While I loved the HE-400's bass, my ears just got tired of the whole thing after a while. It was fatiguing even after I EQed the treble down by about 12 Db at 10KHz. I wanted to try a something warmer, and reviews of the Vibro had me intrigued so I bought them.
 
System
 
FLAC and 320 Kbps mp3 through Foobar to a Concero and Project Ember at home. I also used the Vibro with my Fiio X1 and Cayin C5 at work. I mostly listen to electronic, rap, rock, and metal in that order.
 
Now for the breakdown. I'll start with overall strengths and weaknesses and elaborate below.
 
Strengths
 
Gorgeous, luscious, detailed, enveloping mids
Warm but still very clean, not thick at all
Natural tonality. Very relaxing and immersive. These are headphones that present music as a coherent whole rather than as a sum of technicalities (which is not to say the technicalities aren't still done well)
Smooth, never offensive treble
Extremely forgiving--I've never heard bad source material sound so good
Open and airy. Don't sound closed. 
 
Weaknesses
 
Generally on the soft side. Too relaxed for aggressive music
Bass lacks ultimate extension and impact
 
 
OK, on to the specifics.
 
Bass
 
I'm a bit of basshead, I'll confess. The bass is adequate but a definite weak point (for my preferences at least). Drums and acoustic instruments sound great--the bass is very natural and it has an airy quality that lends realism to the timbre. With all three ports open and my Cayin C5’s bass boost turned on, the bass quantity is satisfying for EDM though I would still prefer more for rap (for reference, I think my P7s have a smidge too much bass with no boost/EQ, and I EQed the bass on my old HE-400 up by about 3 dB centered at 40Hz).
 
I tested the extension in Sinegen. Extension down to ~20HZ is there but pretty rolled off starting around 50Hz or so. This was especially noticeable when I tried watching Transformers. The Vibro just couldn't create the rumbling, subwoofery ambience of a movie like this. My P7's on the hand scrambled my brains with subbass on this movie. 
 
Quality-wise, the bass is a little soft and diffuse. It doesn't slam as hard as I would like. Again, this is not a problem for acoustic instruments but it is a problem for synthetic sounds. For my tastes at least.
 
Mids
 
The Vibro does mids fantastically. Synths wash over you in warm, shimmering waves. Textures have a soft richness to them, a holographic vibrance that's smooth without losing detail. Voices and guitars simply sound real. All of the details are there with an effortless realism. The mids really could not be better.  
 
Treble
 
I'm moderately sensitive to treble and the Vibro never offends. It's treble is smooth and gentle. While detailed, it does not stand out. I wouldn't go so far as to call it dull, but it does lack some energy compared to brighter headphones. These are on the dark/ warm side after all. The upside is that I can listen to the Vibro for hours without any fatigue, even with poor quality recordings. The treble is very forgiving. I personally loved the treble but I could see some wanting more. 
 
Detail retrieval

Detail retrieval is top-notch. Easily a step above the HE-400. The Vibro doesn't spotlight detail the way brighter headphones do, but if you listen closely a lot of information is there. I found myself hearing things I had never heard before with the HE-400.
 
Soundstage and Imaging
 
I was a little concerned about the soundstage after ordering these. They were my first high-end closed headphones. I was not disappointed in the slightest. The Vibro simply doesn't sound closed at all. The soundstage isn't the widest in the world but it's plenty deep and instruments have room to breathe. Separation is excellent, though the Vibro doesn't have razor-sharp layering like the HE-400 did. Rather, imaging is more diffuse. The layers blend together without ever sounding crowded. Distance-wise, the Vibro is neither upfront nor distant. Its soundstage is presented in a very natural way that doesn't call attention to itself or get in the way. 
 
Genre Appropriateness
 
I listen mostly to EDM with some rock and rap thrown in. The Vibros are great for rock. I don’t really care about subgenres so I’ll just name some bands that sound great. The Cure, New Order, Fleetwood Mac, The National, The Decembrists, M83, Tool, Isis, and many others. Guitars, synths, and vocals are all wonderful, and the bass presentation does well with drums and bass guitar.
 
EDM-wise, the Vibros do fantastically with lighter poppy stuff like Neon Indian, Baths, or Chvrches. But when it comes to music driven by the bass like Recondite, Com Truise, or Crystal Castles, they fall short. The pounding beat just doesn’t grab me the right way; the sense of drive is lacking. And while the Vibros do synths in a gorgeous, shimmering way, they can’t give them that ripping, buzzing, sharp texture I enjoyed from the HE-400. Likewise, rap just doesn't have enough weight for me. 
 
For both EDM and metal, it's worth noting that the Vibro's forgiving nature is a major asset. It gave new life to recordings that I generally skipped over with the HE-400. I felt like I was rediscovering some of my old favorites that hurt my ears before (Wumpscut, looking at you). 
 
Ordering, Customer Service, etc.
 
Zach is an awesome guy to deal with. I can't emphasize that enough. He is attentive to emails and you can tell he cares about his customers and his products. He was a total stranger to me when I ordered the Vibro but I moved to Chicago shortly afterwards and met him in person. Getting to know him only cemented my initial opinions. He loves what he does and he'll take care of his customers. He even gave my Vibros a touch-up/ retune before I sent them on to their next owner. Try getting that level of service from a big company!
 
Overall

The Vibros are fantastic headphones. They are both warm and clean, detailed and forgiving, lush and natural. If that sounds like contradiction, it’s not. The Vibro is able to have all those qualities at once by having a relaxed and soft signature. It’s a very pleasing signature, don’t get me wrong, but for my tastes it doesn't work for everything. I wish I could have kept it, I do miss it sometimes, but for me it's too expensive to keep around as a sometimes headphone. 
 
 

Comparison to AKG K340

Just for fun I’m going to add a brief comparison here. The K340 and the Vibro are maybe a little similar in that they are both closed headphones that tend toward the warm, musical side. However, the similarities end there.
 
The only thing the K340 does better than the Vibro is treble. The K340 has an effortlessly fast, detailed treble. It’s clearly brighter than the Vibro’s treble without being that much harsher. It is harsher, but that’s only because everything has harsher treble than the Vibro.
 
The K340 has rich mids, but they have a kind of weird recessed coloration. At least my pair does. The Vibro’s mids walk all over the K340’s by a longshot.
 
I’m going to call bass a tie. I EQ the bass up on both, but my bass EQ for the Vibro is actually 2-3 dB higher at the peak. Similar shape/ bandwidth. I would go higher with the K340 but it muddies up the sound too much. Anyway, the Vibro has better extension, speed, and detail but less body and impact. The K340 is a bit more solid but also slower.
 
Overall, The Vibro is the better headphone. It’s more cohesive and natural. 

​

Tucked away in a corner room, in a non-descript Chicago apartment, the barefooted and bearded Zach Mehrbach works away with scissors and soldering irons, spools of hook up wires and stacks of t50rp drivers, and a host of other tools of his trade. He is the main man behind ZMF Headphones, an easy-going guy that simply loves good sound.

Hand assembled and made to order, Zach prides himself on being a “small shop” headphone builder that caters to his clients’ auditory demands (within reason of course). With the world of high-end headphones seemingly growing every day, Zach is setting himself apart by focusing his attention solely on creating custom orthodynamic headphones based around the ever-popular Fostex t50rp driver and enclosure. While that sounds simple enough, he has spent years extensively researching, testing, tweaking and retuning his modifications to nail down what he considers to be a truly naturalistic audiophile-grade sound that’s “musical, engaging, and above all addictive.”

Originally just a hi-fi enthusiast and headphone modder like many of us, Zach officially took things to the next level when he formed ZMF Headphones in early 2013. Although a relative newcomer to the market, Zach has worked through some early growing pains to rapidly establish a solid following in the audiophile/head-fi world, trusted reviewers sing praise for his creations, and he himself is increasingly making the tradeshow rounds, further building his brand and reinforcing the reputation his personality and customer service have already earned him. 

ZMF Headphones now has four models: The Classic, Master Model, and tunable wood-cupped x Vibro and flagship Blackwood. They span a variety of price points and offer a staggering variety of custom looks, fits and tuning options that allows for a truly unique headphone to be created. 

Regardless of the headphone model chosen, ZMF Headphones’ house sound is resolute on being smooth, articulate, punchy and never sibilant.

In this sense, ZMF Headphones aims at offering a closed-back alternative—or companion—to the many open-back orthodynamic headphones on the market, but with a unique touch of course. Zach’s design is intended to blend the benefits of both dynamic drivers and orthos. As he says, “I have set out to tune ZMF headphones with the engaging qualities of dynamic drivers, yet with the encompassing precision, accuracy and timbre that is often associated with planar magnetic headphones. [By] providing an above average soundstage, a perfect engaging mid-range, life-like bass and smooth highs, users get a headphone that can be listened to for hours on end.”

Some may find that too good to be true, but part of the ZMF Headphones value proposition is that if you don’t like the sound, you can send your headphones back for a free retune based on your wants or needs. This is actually how I ended up spending part of my weekend hanging out in Zach’s apartment and ZMF Headphones headquarters.

 

​

The ZMF x Vibro

Having read many good things about the ZMF x Vibro, I decided to give it a try for myself, picking up a used pair off of Head-Fi.org. They arrived with walnut wood cups, Alpha Pads, buffalo leather headband and Zach’s OCC copper/silver hybrid balanced cable. I popped them on and ran them through some laps on my Woo Audio WA6-SE, ALO Audio Island and Pan Am, Sudgen Headmaster and Yulong DA8. While the x Vibro had plenty of nice characteristics, I ultimately felt that I was left wanting for more; they just seemed a bit too dark, laid back, and even a touch thin at times to my ears, especially when coming from the Sennheiser HD650 that synergizes so well with the WA6-SE, the main amp in my setup. When I posted this statement on a Head-Fi thread, Zach spotted it, messaged me directly, and set out to deliver some top notch customer service.

As Zach explained in his message, the pair that I had purchased was actually one of his early builds. Since then, he has further refined his design, materials and tuning, meaning the pair I had wasn’t quite up to snuff with his current offerings. The cure: Zach had me over (we live within a short drive of each other) to “update” my used x Vibro, something he’s been trying to do to the few older production models still floating around whenever he spots them.

So while I hung out, Zach worked away and then kindly presented me with my “new” x Vibro. Using his measurement software and testing devices, he showed me how his changes improved the frequency response and left the drivers matched to within roughly 1 db of each other. “The better the left and right channels are matched in a headphone, the better it will sound,” he explained. “All ZMF headphones go through rigorous burn in and testing before being sent to the end user.”

So how does a current spec x Vibro sound? Much better and pretty darn good. When Zach writes his product descriptions, he pretty much tells it like it is. I suppose this is part of his craft; he can’t really afford to sensationalize or be misleading when he’s so actively involved and accessible in the headphone community. 

But to get on with it, the x Vibro is a smooth operator. Coming from a Beyerdynamic, Grado or Sennheiser headphone to these, you’ll likely be thrown off by the very different tone and response, but as your ears settle into the ZMF sound, you’ll start to notice just how resolving it can be. 

Throughout the entire frequency range I detect no harshness, no grit, just free-flowing music. The tonal balance is what I personally consider to still be on the darkish side, with a boost in the mid-bass, descending treble response and a mellow mannerism overall that saves your ears from fatigue while still delivering a sufficient amount of clarity. 

Of the headphones I’ve had in my collection, I liken the x Vibro most to the HiFiMan HE-500 when it comes to tone, although, from memory (I sold my HE-500), I think the x Vibro may actually have more engaging mids (more present vocals) and a touch smoother presentation overall. Separation is quite nice with these. The damping and tuning seems to allow you to really pick out each instrument and focus on it, and there’s a nice layering to the sound, especially with high-resolution recordings. For being a closed-back headphone, the soundstaging of the x Vibro is surprisingly good. While the x Vibro has three bass ports on each cup that can be plugged or left open, Zach recommended leaving them open and that is how I also ended up enjoying the x Vibro the most. Plugged, I found the bass could come off a touch cool, but unplugged, the sub- and mid-bass bleeds into the prominent midrange to give these a lusher, more fulfilling sound. 

What I personally find most challenging about the x Vibro is how dependent it is on having strong synergy with the amp it is paired to. An amp that pumps out a strong current into a 50 ohm load is definitely desirable. For example, the x Vibro paired with the Woo Audio WA6-SE is underwhelming for me. With my ALO Pan Am switched to high gain it sounds pretty good. On the ALO Island it’s decent… certainly good enough for at the office. With the Sugden Headmaster, the x Vibro begins to show some real meat. But when matched with the Decware Zen Taboo, purposely designed for planar headphones, the x Vibro absolutely sings; it’s like a completely different headphone. My point here is that amp matching is critical if you want to get the most out of the x Vibro, otherwise you likely stand to be disappointed. This isn't necessarily a bad thing, but it is a valid point to consider before making a purchase.

All in all, Zach is a standup guy crafting some pretty nice custom headphones under the ZMF Headphones label. He truly stands behind his products, so if you haven’t already, check out ZMF Headphones.

Now here’s a look behind the scenes….

 

ZMF Headphones headquarters

​

 

Zach making upgrades to my x Vibro

​

 ​

Drivers being matched for a large order

​

 

Carbon enclosures in different stages of assembly

​

 

Custom colors for the ZMF Classic

​

 

Zach in his listening chair

​

 

ZMF x Vibro in Cherry

​

 

ZMF Classic

​

 

ZMF x Vibro in Walnut

​

​

 

​

First let me just get this out of the way and say I absolutely love these headphones, but this review is completely subjective and in that it is only my preference and opinion on what this headphone offers it would be owner's at the price you pay for such a product. I have use this headphone with a few different amps, desktop and portable, and a couple different sources. It has sounded enjoyable with all of them but of course there was better synergy with particular pairings. Which I will talk about during my impressions and review from over time. This is a list of the amps and DACs used during the time I have used this headphone: ALO PanAm(DAC and amp), Geekout 1000(DAC and amp), Matrix 2012 edition(amp), JDS Labs C5(amp), Meier 2Move(DAC and Amp), Cayin C5(amp), W.S. Blue bird 1.2(amp), Cmoybb(amp), and rockbox iPod 5.5(DAC). 
EDIT: Audio GD NFB 28(DAC amp)
 
I will say I think that this being an orthodynamic headphone it does need some power to be driven to a clarity and detailed musicality that the headphone excels in. This is just my opinion and though particular pairings were not as good as others, I still really enjoy all these amps with this Headphone. Now to get into the actual review.
 
Build/design:
 
 Well first off you have options for this customize T50RP modded headphone, and when I say modded I mean modded... it really is so much more than you would ever get from your standard model. It is aesthetically beautiful, and I mean I think that many people would like a pair just on the looks of the wooden cups and stained finish. You also have the choice of the the leather comfort strap for weight dispersion on your head which helps with comfort overall, because let's face it this is a heavy headphone which is from the wooden cups and ortho drivers. It is definitely also one of the most comfortable headphones I have worn, and that is a testament to the leather ZxV headband strap and the alpha dog ear pads. So comfort I would give a 9/10 only minusing a point for the overall weight still being a factor. That being said I feel like Zach working with Vibro labs is one of the best things that has happened for the T50RP, being that this headphone at full retail is cheaper than both the Alpha dogs and the Paradox slants. Granted these are all different sound headphones and from what I have heard the Alpha's are a bit more precise and neutral, but I feel the ZxV's are more musical and overall more enjoyable.
 
Sound: I will break it down in a few sub categories to give myself and the would be reader's a break.
 
Lows: The bass is a variable option here with the bass ports, and their plugs. You can choose how much bass you want from this headphone to a certain extent, and honestly it really does make a difference. I personally think it sounds best for the genre's I listen to mostly with 1 stopper out of 3 removed on each cup. This gives me nice impact with out sounding to loose and or sloppy for some of the more bass intensive tracks. I have listened to every option so I can say that even all ports closed the bass has nice impact and a special character, the lows are definitely good, maybe not as tight and as in depth as I would like with some of my music but still good. 8/10
 
Mids: This is the bread and butter of this headphone, honestly I do not think I find anything wrong with this at all. I mean that, and yes the midrange is lush and slightly fuller and warmer. But it is never lacking detail and extension from what I can hear. also it has magic. Yes, Magic is what I said, I normally do not think of a magical element when referring to a headphone except the few that I reviews passionately.  This midrange just is immersive where it surrounds you intimately is presented in a way that it is very very hard to forget. I think it is beautiful, and I am not even saying this is my ideal midrange, I like open headphone, but even the HD600s/650s did not effect me like this with their midrange. I think it is still smooth and lush without dropping detail and speed, and clarity is still decently good. 10/10 this was the easy one for me to rate.  
 
Highs: Smooth is a word that comes to mind when listening to the high range, and it still retains decent detail, but not as much as I sometimes would like with specific genres or groups. I definitely think it is nice sounding, and still enjoyable and for someone that does not like bright headphones this is definitely a good thing. This is a tad on the darker side but the more they opened up with use, I will be honest they do not feel as dark as they did. Certainly more neutral than the ZMF V2's. This  was one of the harder things for me to rate, because though it was a smoother treble it was still detailed well enough and most importantly I kept putting these headphones back on over everything else I compared them with... 7.5/10 I believe this is fair.
 
Soundstage/ imaging/ separation: this is not going to take the medal for openness and stage for it is still a closed headphone, but this definitely feels more spacious and deeper than other closed headphones I have listened too. The T70p is wider by a little bit but also feels less natural, and HD600 feels more grainy. So, it may be closed but it does have some space and good separation for sure, The imaging is easy to pin point instruments and feels very 3d to me. I have to be fair and keep my thoughts realistic on the soundstage, because this is closed so with that being said 8/10(imaging and separation top notch for this price, staging not to far behind for a closed headphone)
 
Timbre/tonality: Impressive, and very real feeling to me, yes it is a tad warm in somethings but still very natural and god do I love it's overall tone. Could be because of the wooden cups, and or just the modding Zach has done, but I will be talking to him more and editing this review along the way. 
 
Comparisons: This beats out, for myself, the HD600/650s, Beyerdynamic T70p, DT880s, Dt990s, and comes closer to the Hifiman HE-560 level of headphone. Now, this is not objective just opinion, do not want to step on any toes. I had sold all my headphones but kept these, and now the HE-560s. They make a fantastic partnership. This Headphone is similar to the HD650 in it's intimate midrange, and nice bass impact. smoother sound sig. But It just did things better imo. Detail and musicality won me over in the end. 
 
Amp pairings: out of those listen above I will be honest in saying I did not expect the GeekOut 1000 to pair so magnificently with this headphone. But it did.... it is an aggressive DAC/Amp Class A and god does this sound good together, adds tightness in the bass and extension up top. With improving further on clarity, detail, and speed. Making this a very awesome combo.
 
Now originally the ALO PanAm I had thought only decent with the RTC French tubes but once I put the Geekout1000 as the DAC and PanAm as amp(with the Cifte tubes) I was much more impressed where the bass was tighter and quicker, but the midrange was even more detailed and musicality was done justice. Very nice and sweet pairing.
 
Cayin C5 would be the amp that I recommend as far as portable listening with this headphone as it has 850mw of power ouput, and is able to drive these to a very nice level of both clarity and detail, they pair very well, because the Cayin C5 for a lack of better words is a beast of an headphone amp(taken from a friend :-D) 
 
The JDS Labs sounded okay but lacked in power at the impedance of this headphones and just did not able to get best sound from this. At lower volume it sounded okay and still enjoyable because both these products are good for their price.
 
Meier 2Move is more musical and slightly more warm than the JDS Labs C5 and I enjoyed it more because of this. Was a good match and recommend after the Cayin C5 and W.S1.2 Blue Bird
 
Finally the Audio-Gd NFB28, is probably my favorite DAC/Amp paired with this headphone, and that is out of the single ended jack, which this being a fully balanced unit I am waiting on a cable actually from Zach to test from the balanced jack with a 4pin xlr plug. I think the Speed of this amp and detail really add something to the ZxV and if anyone is looking for an all in one unit with lots of options for connectivity and inputs and outputs this is the way to go. 
 
Overall: This is my favorite closed headphone and possibly my tied for favorite headphone I have owned, next to the HE-560 and especially after the pairing with the NFB28, I think from the aesthetics, customizing, build and comfort all the way to the tonality, musicality, and detail of this headphone you are in for a real treat and bargain for 550$. You can also find out about possible B-stock(if available) and other options from Zach, who is very very good at getting back to people. Hell, he has even talked to me just about possible amps to try cable, etc. When I had already bought and been using his HP. Great guy, great company in the rise, and magical headphone. Not much to complain about just think to your own preferences before buying because that comes down to a big chunk of what you should choose.  
 
EDIT: once I get the balanced cable from Zach, I will be pairing the ZxV with the NFB 28 balanced jack and see if there are improvements and or differences worth writing about. Also, any amps I try that I think worth mentioning as well. I am sorry to those who wanted an objective review on this headphone, that is just not what I am capable of at the moment. I hope this review helps any fellow headfier out there looking for a headphone.
 
EDIT: Received the hybrid copper/silver balanced cable and extensions from Zach today. I originally had been pairing the ZMF x Vibro's with the Audio-gd NFB 28, which had been the best pairing I had found for the ZxV to date, and adding the "hybrid" intertwined cable and plugging this already great headphone in to the balanced jack just made things that much better. Given this is a fully balanced system and it's purpose was meant thus, so single ended sounds good but is about 10% maybe more less in sound quality and about half the power of the balanced jack. I will say first impressions are very positive and instantly realized the differences in improved clarity, speed, details, and power. The harshness that happened in the treble times is gone completely with just a more detailed and refined treble making this one of the best pairings I have tried let alone owned.  
 
Edit: So, firstly I have found the best pairing to date with my own subjective experiences with the ZMF x Vibros headphones. It consists of a transportable set up of the iBasso DX90 paired with PB2 balanced portable amp to balanced adapter to 4pin xlr to the ZxV headphones. It sounds crisp, powerful, yet does not loose that midrange and impact in the lows. It  is like listening to a desktop setup in my experience. I highly recommend it if possible looking for an amp for this headphone search the classifieds on the FS forum.

Disclaimer: I have been talking with Zach of ZMF Headphones quite a bit over the past couple months with some ideas that might help him refine the ZMFxVibro headphone based on my thoughts and analysis of it (have tried a couple pairs and couple revisions), so there’s bound to be some inherent bias in my opinion. However, I do strive to minimize any bias and take pride in trying to provide the community with honest, transparent reviews and at least a somewhat objective, but digestible, analysis of products. In other words, I'm trying to break the mold compared to what you get from typical industry insider and/or overly-excited reviewers. I am in no way affiliated with Zach or his ZMF Headphones company, nor have I or will I receive anything whatsoever from our discussions, any ideas we've shared, or this review. 
 
This is a loaner pair that I am reviewing. This review is based on the latest tuning as of mid-September, which should be the final revision except for a couple other changes that won't affect sound quality. More on that later.
 
This review was posted elsewhere on the internet a few weeks ago and has been edited and refined in some ways.
 
Introduction
 
I wasn't sure what to expect from the ZMFxVibro when I first got a chance to listen. It had a lot of promise, but I thought it needed a couple tweaks to smooth out the treble. I experimented a bit and found something that really made the ZxV sing...just some basic front damping. Zach happened to contact me, we had some good discussions about the headphone, and we tossed some ideas around. A few weeks later, he sent me a set of revised headphones with some internal and external damping changes, including some new front damping (the key factor). I was curious to hear how his changes sounded compared to the previous pair I tweaked on the front side a bit, which I had quickly grown fond of. I was happy to find that the changes with the new pair were to my liking...surprisingly so. I thought they sounded pretty darn good! But, let me not get too hasty with those details just yet, so I'll get back to the sound and even offer some Alpha Dog comparisons in a bit.

Looks, Comfort, Build Quality, Presentation, Misc.

I have to say, I think these are a good looking set of headphones, though I like the look of some of the other pairs on the ZMF site even more (Zach wasn't crazy about how porous the type of wood on this particular pair was). On this tour unit, the blue finish and particular type of wood makes for an interesting and, in my opinion, beautiful look. You’ll recognize the classic T50RP headband, and ZMF offers custom re-finishing on the metal railings as well. There is a nice set of finish options, both wood and railings, to choose from. Here's a shot of this particular pair, though it doesn't do it justice in any way (screenshots on the ZMF site are much better):
 


The variable bass-tuning port implementation works fairly well and does what it is supposed to. Essentially, it offers 4-stage tunable bass with the 3 ports (fully closed to fully open). While I prefer the implementation that allows you to finely tune the Alpha Dog, the ZxV’s venting options is much more convenient to utilize despite being less granular. And where as the AD isn't meant to be tuned more than once or twice, and is harder to get perfect without fine tuning, the ZxV's solution lets you adjust the tuning on the fly. Of course, there are other headphones with tuning options, and I even remember seeing some early T50RP mods with similar ideas.
 
I found I preferred having one port open per channel on the ZxV, as having them all closed made them a bit too weak sounding, and any more made them too bass heavy for my tastes. Having more ports open can be fun at times, though, and I think it's great to have that option for those with varying tastes. To be fair, Zach was targeting a headphone that could be rather bass-heavy and lush sounding. My impressions and measurements were done with my preferred configuration, only one port open. One downside to this venting setup, however, is that it’s pretty easy to lose the dowels if you aren't careful. A good example would be if you're adjusting the headband sliders and rub your hands against the dowels. There's a good chance some will pop out.

Thanks to the alpha pads and padded headband, the ZxV is a fairly comfortable headphone. I still think the Alpha Dog itself is a bit more comfortable and fits better on and around the head with the suspension-like comfort strap, as the ZxV’s wood cups and overall method of construction make for a more rigid headband and fit. The main factor, as I see it, is that since the cups are entirely rounded, there is no recessed spot for the headband rails to bend near the top of the cups for fit purposes. The way the headband screws into the cups might also be too rigid. Good thing the T50RP headband can be bent without much worry. With some brute force, I was able to bend the headband to a shape that gave me a good fit and seal, if not yet quite perfect like the AD.

Overall, the Alpha Dog feels like a more premium, well put together product, and the ZxV has a distinctly hand-built look and feel to it. Still, the ZxV does have its aspects of beauty and is certainly more than functional in all the non-sound areas, so I'm really more concerned about how the headphone sounds when all is said and done. ZMF does offer some other optional accessories to purchase along with the ZxV, such as a nice, hard carrying case and braided OCC cables.

Sound

I think the ZxV is a very enjoyable headphone to listen to, plain and simple. They are a bit on the bass-heavy, slightly dark side, but generally have a surprisingly good sense of balance and neutrality to them. Mids are not scooped, and treble detail doesn’t appear to be missing despite it being a touch dark in spots. Perhaps the ZxV is not too far off the HD650 in that regard, though it is less laid-back sounding. At times, the bass can be a bit disconnected sounding on the ZxV, but the sound does tend to be rather cohesive as a whole. I thought the bass sounded fairly clean and offered good pitch and detail. With one port open, sometimes I wish it was still just a bit less powerful, but I often like the tasteful bass bump. It makes music sound lively, and the T50RP can start to sound weird if you start lowering the bass too much, even if it measures flat. Perhaps this is due to the small, planar driver, and maybe the driver has a need for some amount of venting

Subjectively, something about the upper-mids and treble can be a bit edgy sounding, not unlike how the HD600 can be at times. The ZxV also can be a touch harsh or, perhaps better put, hashy sounding, but this never really bothered me or got in the way of enjoyment for long listening sessions. It’s probably just my quite sensitive ears given how slight it is. It's more noticeable coming from smoother sounding headphones. It was still smoother and less artificial sounding than the Alpha Dog and maybe sits somewhere between the HD600 and HD650 in terms of edginess and smoothness.

That said, I do think the ZxV offers a good sense of clarity and blackness, more so than the Alpha Dog. The ZxV might also be a faster and more resolving headphone than the AD. I often found the ZxV did a slightly better job pulling out low-level information, and it did a better job on one of my sample tracks by bringing out the fast snare beat and associated detail (blast beat section of a metal song, very easy to muddy up). If anything, despite being a bit less neutral sounding (except for bass), darker, and lusher than the AD, it has bit more of a “hi-fi” sound to it. Don't get me wrong, as the ZxV is still quite neutral to my ears. The AD noticeably excels when it comes to soundstage over the ZxV, as the ZxV is more on the closed sounding or intimate side, but the ZxV does seem to do well or even better with separation regardless (and that extra sense of clarity helps). I found the ZxV to be a fairly organic sounding headphone when compared to the other headphones I have on hand, which is something I prefer over the AD’s presentation. I might even find it more organic sounding than the HD600/650, even if you dampen and mod those Senns, but it’s hard to say and depends on my listening mood. I think the ZxV has pretty good tone and timbre to it, and one I almost always preferred over the AD. I wrote a note saying the ZxV can be a bit nasally at times. I guess that is true, but very minor and no worse than niggling issues I’ve heard from about any headphone.

The ZxV does appear to have a tiny bit of channel imbalance, but this is largely fixed if you fiddle with the fit and placement. Really, it doesn’t get in the way and usually isn’t noticeable. The AD suffers from this too to an extent, but perhaps less so. I think unless you are meticulously trying to match channels, there are some inherent limitations with the T50RP drivers.

Compared to the OPPO PM-2…I dunno, I think I just like the ZxV more in most regards. It makes the PM-2 sound boring and lacking something.
 
I also was able to test the Paradox Slants for a while, but those are not too comparable to the ZxV or Alpha dog, in my opinion. The Slants have more of a bass emphasis in the 100-300Hz area (a thicker, more wooly sounding bass), more relaxed upper-mids and lower-treble, and are generally just a bit more laid-back sounding in a way. The Slants are quite refined sounding, probably the best of the bunch, and look great, but they're occupying a different sound signature than the ZxV or AD. I haven't heard the regular Paradox recently enough to comment on it.
 
I might even prefer the ZxV over the HD600 or HD650 in back-to-back listening tests. Hard to say. Overall, despite the ZxV not being perfect, these are one of the more enjoyable headphones I’ve tested recently, and I did find myself gravitating towards the ZxV during my back-to-back tests. Very highly recommended from a sound quality perspective!

Measurements
 
Note: My measurements are not comparable with results you'll find elsewhere. As it stands, flat on my frequency response measurements sounds pretty flat to my ears (not necessarily your ears), so you shouldn't have to strain too much trying to figure out how to correlate these with my subjective impressions. I do not guarantee absolute accuracy of any of these results, but they are very useful at times. Roughly calibrated to 90dB at 1KHz on the left channel.

Frequency response measurements do show an overall slightly dark tilt, but the midrange is pretty good and even. There are some channel imbalances evident below the treble area, but I didn’t ever find this subjectively detrimental. I've seen this on other T50RP mods too to an extent. Keep in mind the scale of the FR graph is only 30db. Bass is a bit elevated, but sounds tasteful to me. The treble is a bit uneven and depressed in some spots, but that doesn’t seem to contribute to anything sounding particularly weird. Still looks better than the PM-2 to me and quite a few other headphones. That dip around 8-9KHz is probably a measurement artifact.
 


Zach and I have had some discussions about internal damping and reasons for this pair’s channel imbalances, and he is pretty confident current production pairs should match a bit more closely than this. Based on what I know about this pair and some advice I gave Zach from that, I’m inclined to think he is probably right, and it’s not anything that will affect the overall sound.
 
I don't think I grabbed measurements of other port tuning configurations, but it does what you'd expect by primarily lowering or boosting the bass response below 150Hz or so.

Distortion results overall look pretty good, especially on the right channel. Arguably smoother and cleaner, though not necessarily lower on average, than the AD’s results, which might contribute to the subjectively more “hi-fi” sound and clarity I heard. There is a bit of a rise in bass distortion, but this is still a pretty good result. The distortion spikes in the left channel didn’t seem to impart any negative subjective characteristics when I was listening, and, again, based on what Zach and I have discussed about the internals on this particular pair, this should be ironed out in current production pairs. Even if the channel imbalances and harmonic distortion oddities were to not be further ironed out, I don’t think it’s worth worrying about. (Remember, D2 = 2nd order harmonic distortion, D3 = 3rd, and so on. If distortion is 40dB lower than the response at any given point, that is roughly 1% distortion. 50dB is about 0.32% distortion. You can find calculators online for this. D2 is often equivalent to THD results.)
 



CSDs look pretty clean, which isn’t unexpected for a T50RP mod like this. The extra bit of decay around the 2-3KHz area might factor into the edginess I was hearing, but even that is pretty minimal. I don’t think most will have issues or even notice what I was talking about. There might also be some extra resonance below 1Khz that affects the sound. If you compare with the Alpha Dog CSD measurements in the review I posted for that headphone, you might notice the AD measures with a bit more resonance below the 1KHz spot or so. This might also contribute to the slightly more "hi-fi" sound I heard on the ZxV.
 


 
Raw measurements show us that the ZxV is a pretty consistent performer, though you can see some changes based on fit and placement differences. 
 


 
And now for some comparison frequency response measurements! For other comparisons (such as CSD or THD), you'll need to pull measurements from my other reviews or sources and compare on your own.
 
First up is the ZxV vs Alpha dog. You can see some similarities, but they are tuned differently. The AD has a bit more bass, less of a smooth bass-to-mids transition, and somewhat of an emphasis around the 5-6KHz region where the ZxV is a bit darker (I think this is part of the reason I prefer the ZxV's tone and find it a bit smoother on the ears). Both have a dip around the same spot in the treble, which makes me think this is an artifact inherent to the T50RP + alpha pads in combination with my measurement setup. Overall I think the ZxV looks a bit smoother and more balanced. They sound less similar than you'd think based on the graph, and I can only make guesses that they aren't using similar internal damping schemes or materials.
 

 
Figured I'd compare it to the classic HD600. Again, this might explain why I prefer the ZxV's balance.
 

 
Here is a comparison with the HD650. Interesting! I do like the HD650 quite a bit, and it seems the two headphones have a similar target curve above 1KHz. The HD650 is a bit more mid-bass heavy, not quite as lively sounding, and doesn't quite have the same low-bass impact as the ZxV.
 

 
Again, fairly interesting. The PM-2 sounds pretty "weak" in terms of impact and power compared to the ZxV, though you could argue it is more bass-neutral, and there is a noticeable chunk of missing treble information during listening tests on the PM-2 (see the PM-2's big treble recession). The PM-2 also has rougher sounding treble. Might not be as clear sounding as the ZxV. Personally, I had no desire to use the PM-2 when I had the ZxV on hand (keeping in mind I only really listen at my desk).
 

 

Conclusion

The ZxV might not have the perfect build or looks of the Alpha Dog or PM-2, but I simply really like how the ZxV sounds. The original pair I heard was a bit uneven and too harsh in the treble, and I think Zach did a good job targeting the sound he was looking for in the end with this pair. The ZxV now employs some front damping to help smooth out the sound, and I think the materials produce good results. Perhaps there is still room for improvement with other front damping materials and configurations, but I’m pretty satisfied with this. Oh, and if you get a ZxV and want more treble, try taking off some of the front damping material directly in front of the driver.
 
I was tempted to give the ZxV a 4.5/5 given how good I thought it sounded, but I'd like to see a bit more refinement in both how they fit on the head, which may require too much work with the cups as they are, and a bit more refinement in some elements of the sound, such as more tightly matched channels and tweaks to better ensure low harmonic distortion. Some of the hand-built aspects, while they have their charm, also keep me from going with a 4.5/5. So, with the solid 4/5 score, keep in mind that I still really dig how these sound and suggest you not overlook them! I'm excited to see what Zach is able to provide in the future.