Massdrop x HIFIMAN HE350


New Head-Fier
Pros: Great build quality.
Cons: Bass-light.
Ridiculously overdone highs. Practically hissy.
These cans are a disappointment. I spent an hour comparing these against the much cheaper Superlux HD-668B (~ $40), and the 668B is better in ever way except build quality.

Switching from the 668B to the HE-350 is painful. Sound seems muffled. Both are sparkly at the high end, but HE-350 is definitely more hissy. Mids feel distorted, and low bass pretty much disappears. Switch from HE-350 to 668B, and there's a marked increase in clarity. Separation between instruments seems to be better and the bass is hands-down better. The 668B is just way more fun to listen to.

The only thing HE-350 has going for it is better materials. It costs 2.5x as much so that's not surprising.

I sold these without using them at all. Unless you know you can put up with super-bright highs and a lack of bass, avoid.


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New Head-Fier
Pros: Good detail retrieval, wide soundstage
Cons: stock pads are not comfortable, pad rings very brittle, treble incredibly harsh, lacks bass
If you're looking for your first audiophile headphone for home usage, these may work well for you. The detail they offer is superior to mainstream consumer market headphones.
However, if you own and listen to high end gear, I would not recommend these headphones.
First of all, I disagree with the praise the Hifiman HE350 get for comfort: I found these very uncomfortable to wear because the pads are very hard. To make matters worse, changing the pads is a pain, because upon removing the stock pads, the plastic rings of my pair snapped because they are so brittle.
After re-gluing the plastic pad rings, I tried the following pads, which all had different effects to the music:
-HM5 Angled Velour: increased comfort drastically, smoothened the treble significantly, but they lost all their punch, making them sound very boring.
-HHM5 Angled Leather: increased the comfort as well, the treble remained the same but the pads increased the bass (because of the seal), giving the illusion of less treble. There was also much more punch.
-Hifiman focus pads: increased comfort, treble slightly reduced, slightly increased bass. Wider soundstage. Since they are a hybrid pad of velour and leather, they offer the best of both worlds. They also come with their own pad rings, so you don't need to spend hours trying to fit them on like the other pads I've mentioned. If you change the pads, I recommend you use these.
The mids I feel are reduced, but what I think is happening is that the harsh and abundant treble swallows the mids away. The Hifiman he-350 are awful with electronic music, making you want to take them off immediately off your head. With classical, they actually sound fairly good, but certain notes from violins and trumpets may sound too shrill.
I mentioned that the bass was fairly lacking in these headphones. To fix this, you can remove the outer rings to access the driver, and there's a sticker covering a hole in the centre of the driver. Move it down so that it no longer covers the hole, and put the cover back. The result is slightly increased bass, though I would still call the Hifiman he-350 bass-light.
However, after all this work and effort pad surfing and driver modding, I still do not like the sound they produce. If you're a mid-fi/hi-fi audiophile, you already have headphones that produce more detail, have a more smooth and less tinny treble and have more bass; but as somebody who has never bought an open-back headphone before, yes, I would recommend them since they are still an upgrade from your mainstream cans. The lack of bass may annoy you though.


New Head-Fier
Pros: Treble and general resolution
Cons: Allthough wide, soundstage is not extremely detailed
Dynamic headphones by the primarily planar producing HiFiman, very good value(especially if you live in america).
Detailed and strong treble, decent mids and midbass yet a little light on lower bass frequencies.
Not as detailed and well rounded as, for example, the HD600, but still a great value.
Comfort is ok, the headband is nice and the cans themselves are very light, but the pads are very stiff unfortunately.
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New Head-Fier
Pros: decent soundstage at this price
Cons: cheap feel, horrible audio resolution and its too bright, terrible EQ
made it look like he-400s 400i or 400 from outside but once you wear it, you can tell it is really cheaply made and audio resolution is like so bad, worse than some of 20 dollar headphones.There are many better option at 100 dollars, including sennheiser hd558 hd518 hd555 or akg k612. I want my money back
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Wow... This is surprising.. how long this have been burned in?


New Head-Fier
Pros: Cheap, Wire is better than MOST HiFiMans, Acceptable Sound Stage
Cons: Uncomfortable Pads, Highs are forward, Plastic construction
When these went on sale at massdrop I thought I was going to put one over on the man and get some really good audiophile grade headphones for $100, sadly that's not what I got when the package finally arrived (nearly two months late).
The HE-350s LOOK like every HiFiMan can you've ever seen, however, that's pretty much where the similarities end. You pull them out of the box and you immediately notice that they DIDN'T use their normal stupid mini-coax plug, and decided to go with a slightly less stupid dual 2.5mm cable. It's at least a step in the right direction on the cable front.
Next you touch them, and where you might expect aluminum or magnesium from HiFiMan, you're greeted by plastic. Ok, they're $100, I guess I can let that slide.
Then you put them on your head, and before music ever starts playing your ears begin to SCREAM at you. The pads are simply unacceptable. In no world should ANYONE be subjected to the feeling of the stock pads. The foam is hard as a rock, and makes these one of the most unpleasant pair of headphones I've ever worn. They're right up their with stock Fostex TXXRP's when it comes to stock comfort.
I tried listening to these with my normal favorites, but I'm not sure if the stock pads were just irritating me to the point I couldn't concentrate or what, but I just remember being angry, thinking the highs were too forward and that there wasn't a normal "open" sound stage.
I replaced the stock pads with Shure 1840 pads, and things got better. The highs are still decently forward, the bass is surprisingly good, but the clarity that I was hoping for is no where to be found. The mids were so washed out that my favorite tracks didn't sing like I'm used to. Imaging is exactly what you'd expect with treble forward headphones, very exacting. Sound stage was still meh. I think my RBH EP3s IEMs have nearly the same sound stage.
With Shure 1840 pads, I'd say you could live with the HE-350s, but I'd rather spend my money on a pair of SHP9500s, and get something awesome straight out of the box for a few dollars less.
I was hoping for more since HiFiMan put their name on these, but they definitely didn't deliver. They're $100 headphones that sound like $100 headphones. You're definitely not getting a deal here.
Tested on Modi 2 and Magni 2 Uber.
glad I decided to get a refund when they pushed the postage back like 2 months or something 
I was told the 350s are not fantastic but I wasn't aware it was THAT bad. I needed a honest review 5 months ago and I didn't find any and now I'm glad i didn't jump on it.
Well, they're a $100 headphone that sounds like a $100 headphone...It's not their fault the Phillips screwed everything up with a $60 headphone that sounds like a $150 headphone. Stock comfort though...that is definitely their fault.


100+ Head-Fier
Pros: Great looks, comfort
Cons: Poor sound quality, cheap materials
I have to give Massdrop a lot of credit for trying to bring high-end audio to the masses through their audiophile community. Those behind their initiatives have managed to bring together companies like AKG, Fostex, Grace Design, ZMF Headphones and now HIFIMAN, among others, to offer some great hi-fi products at affordable prices. So when I saw the drop for the $99 Massdrop x HIFIMAN HE-350 headphones, I thought it would be a great opportunity for new audiophiles and veteran headphone enthusiasts alike to pick up a pair of quality headphones to knock around with on the cheap.

Unfortunately, in my opinion, cheap is mostly what you get this time around. Massdrop made a noble effort with this headphone. It looks great in a sleek metallic gray and black finish; it’s super lightweight and comfortable to wear with the improved headband; it has a custom easy-to-drive dynamic driver and new cable connections so you don’t have to fumble with HIFIMAN’s old screw-on coax connectors of the past. On paper, the HE-350, modeled as a successor to HIFIMAN’s entry-level HE-300 headphone, screams value. On the ears, however, it sort of just screams. Let me explain.

Once the music gets flowing, the HE-350 may singlehandedly be the oddest sounding and most difficult headphone for me to describe fairly. At times, its easily one of the brightest headphones I have experienced in my audio journey to date. I have owned and demoed far more headphones than I have reviewed on this blog, and not one gave me the listening fatigue in such a small amount of time as the HE-350. What’s more, its unbalanced sound leaves you guessing at what you might get. Tracks leaning exclusively to the high side can sound decent. Mid-range-centric tracks are rendered OK. Bass heavy beats hit with some hints of sub-bass SPLs. But ultimately, when everything comes together, as is common when listening to most albums, the HE-350 doesn’t particularly shine in any one area. In fact, to my spoiled ears, it seems as if it can’t keep up, getting overly bright on the top end and muddied up in the bass regions, and the mids often get lost altogether.

I wanted to like these headphones—I’m a sucker for a hi-fi bargain. I was hopeful that they’d be my secondary desktop cans that I toss on while editing photos or freelancing late into the night. But the moment I put these babies on, my ears were hit with overly-emphasized treble that simply left them begging for some balance. I’ve generally enjoyed my HIFIMAN products, but the HE-350 is unlike any others I have heard, and it left me seeking the meaty mids and brutish bass I desire in my listening experience. As a “cheap” headphone, I didn’t expect it to rival my high-end headphones in these departments, but even at this price point I expected more—mostly because it’s a HIFIMAN product, and Massdrop has successfully brought quality without the cost many times before.

I may sound overly harsh here, but the HE-350’s treble is harsh. At low volumes it comes off as crisp and fairly detailed, but as the volume increases, so does the graininess, and with it comes a loss of clarity and enhanced edginess. “Pork Soda” off of Glass Animals’ How to Be a Human Being is a complex track with many layers. It starts out sounding fine with a moderately clean, punchy bass line that the HE-350 manages to move, as the vocals kick in though, the pitchy characteristics of the HE-350 become a bit overwhelming and only intensify as the track gets more complex as it progresses. For those familiar with some of the affordable Grado and Beyerdynamic offering's, I'd say the HE-350 has some of the grainy treble traits of the Grados with the sharp sizzle of the Beyers.

Moving into the mids, I simply find them to be overpowered by the treble. My test for midrange includes John Butler’s “Ocean,” a nearly 12-minute epic studio guitar performance with plenty of complex tones and heart. The HE-350 never quite dug as deep to reproduce the full-bodied sound this track has like I would expect out of a headphone aimed at hi-fi enthusiasts. The same goes for tracks like “Eyes Wide Open” off of Ambient Jazz Ensemble’s Suite Shop (definitely worth checking out)—the horns have no gusto and the layers of instruments simply sound thin across the board without much separation.

As for the bass, sometimes it surprises with a powerful delivery and other times it sounds rough and tumble. There’s something there, no doubt, but when pushed it falls apart pretty quickly. The textured deep bass lines in Moderat’s “Bad Kingdom,” for example, leaves the HE-350’s bass region in a rumbling, sloppy state. But then on Glass Animals’ “Season 2 Episode 3” the bass lines seem to hit fairly cleanly and gets my head bopping just fine.

The more I listen to the HE-350, the more it confuses me. Sometimes it sounds pretty darn decent for the price, and then a track later I can’t get them off my head fast enough. Sure, I could try to tweak EQ settings on my PC setup, but that’s not my style. I want to hear the music as recorded and as my headphones can portray it—this is often where the term, “you get what you pay for” resonates well in audio (just beware of diminishing returns). I tested the HE-350 on various setups (FLAC files via a modified Squeezebox Touch into a Schiit Yggdrasil DAC feeding my Eddie Current Balancing Act and HIFIMAN EF-6 amplifiers; FLAC files on my Hidizs AP-100 DAP; streaming Spotify on my smartphone; CDs through a vintage transport and more) and ultimately concluded that it’s just not for me or my musical tastes. Your results may vary.

As for that initial comment about being cheap—the HE-350 borders on feeling brittle (to me). The lovely box it arrived in actually feels more robust. The nearly all plastic construction has me concerned about long-term durability. Yes it makes it lightweight (congrats HIFIMAN, these are actually pretty darn comfortable to wear), but it feels fragile and, looks aside, doesn’t have the tactile touch of most products aimed at entry-level audiophiles. I suspect some accidentally broken yokes and cracked cups will be inevitable for some HE-350 owners.

I’ve owned HIFIMAN's HE-500; I own the HE-6; I have had HIFIMAN earbuds in the past; I own their EF-6 amplifier; I’ve demoed many of their other headphones. In my opinion, the HE-350 is a missed opportunity. I won’t claim to know the economics behind this project, but I feel that HIFIMAN could’ve in some way delivered something closer to their house sound, which would've made the HE-350 the perfect gateway drug to their line of higher-end products. Maybe it still will be, but to my ears, the HE-350 comes up short.

Listen, the HE-350 is a beautiful looking headphone, it’s comfortable, its detachable cable system is welcomed, and the ergonomics are on point, but the sound quality and overall material feel fall well short of being an “audiophile” product. To those with untrained or unspoiled ears, these may be amazing. But if you’ve already been introduced to high-end headphones, I think you’ll be disappointed. My regular readers know that I tell it how my ears hear it. I applaud the effort behind the $99 HE-350, but I can’t fully recommend this headphone for anyone seeking true hi-fi sound. If you want to try it out, I'd suggest trying to snag a used pair as they inevitably pop up on Head-Fi, Reddit or other audio forums. I look forward to the next collaboration between these two companies, but hopefully the next collaboration of Massdrop x HIFIMAN yields greater results.

  1. Driver: 50 mm dynamic
  2. Impedance: 19 ohm
  3. Sensitivity: 93 dB at 1 mW
  4. Frequency response: 15 Hz – 22 kHz
  5. Velour ear pads
  6. Detachable cable
  7. Cable length: 53 in (135 cm)
  8. Cup connectors: 0.1 in (2.5 mm)
  9. Plug:1/8" (3.5 mm) (1/4” adapter included)
  10. Weight, with cable: 12.1 oz (343 g)
  11. Weight, without cable: 10.6 oz (301 g)
I just got my pair this morning and have been listening to these for about an hour now. This is a tiny amount of time, I know, but I just wanted to throw my 2 cents in here early on (maybe I'll follow up to see how these fare after burn-in [both the headphones and my brain]). 
In some ways, I'd have to say I agree with you that these are absolute Treble monsters. It's great detail and clarity, no doubt, but there's just so much of it. I can also completely agree with the confusing nature of this headphone. Some tracks sound pretty awesome, but others just feel really weak. 

I checked out the Glass Animals track you mentioned, and that sounded great, but then if I put on Green & Gold by Lianne La Havas, I feel like the sub-bass and mid-bass that the track wants to emphasize is almost gone. 
Right now I am in a state where I want to like this headphone, and sometimes I love it, but other times it disappoints me. I guess we'll see with time. 
Thanks for the review by the way! I may just use this headphone to write my first review on Head-Fi :)
If you closely compare the treble of the HE-350 to the treble of other headphones designed for hi-fi reproduction, you'll notice that it really isn't that clear and detailed at all. The brightness of it is misleading in that fashion. But don't let me ruin your fun. If it works for you, great, that's what this hobby is all about.
The Philips 950 sounds much better than the HE350 in every way, and cheaper.
Pros: Acoustically near perfection. Disturbingly cheap.
Cons: Too much upper end energy. Can be fussy with its musical pairings.
HiFiMAN HE-350 Headphone Quick Review by mark2410
Thanks to Massdrop for the loaner.
Full review here
Brief:  HiFiMAN and Massdrop make uber cheap audiophile headphone.
Price:  US$100 or about £76
Specification:  Driver: 50 mm dynamic, Impedance: 50 ohm, Sensitivity: 93 dB at 1 mW, Frequency response: 15 Hz – 22 kHz, Velour ear pads, Detachable cable, Cable length: 53 in (135 cm), Cup connectors: 0.1 in (2.5 mm), Plug: ⅛ in (3.5 mm), Weight, with cable: 12.1 oz (343 g), Weight, without cable: 10.6 oz (301 g)
Accessories:  Errr, a cardboard box for the kids/pets to play with?
Build Quality:  Very nice.  Despite its dirt cheap prices its nicely made, looks good and feels good.
Isolation:  None.
Comfort/Fit:  On and seated instantly, comfort, mostly pretty great.  That upper acoustic spike though did get tiring.  They also just made contact with my ear so after a few hours got wearing.
Aesthetics:  Actually, you know they look really good.  You’d never guess their price form their looks.  Not that any one will ever see them as they are indoor only cans but, hey, you’ll look at them.
Sound:  Great.  Well mostly great, I mean these are audiophile tuned.  There is bass there but it is of a wonderfully high quality at the expense of its quantity.  That means there isn’t much of it.  It is tuned for acoustically perfect classical works.  There it shines, it does some glorious double bass bass, not Miss Minaj when she pulls up her Jag and goes “Dun-d-d-dun-dun-d-d-dun-dun” no sir, these won’t be having any of that.  Of course you can play chavy pop but you probably won’t.  The mids, almost as great as the bass but this time we’ve got a better quantity.  Once more it’s perfect for strings and naturally produced sounds.  Vocals can be a tiny bit dried but for all intents, these are tuned to be acoustically perfect.  Until you reach the upper vocal ranges, into the treble.  There is a great old spike and these have the most laser like focused like sibilant point.  It’s so fine, so lethally razor sharp its more like that of the world’s finest samurai sword.  So polite, so refined, then with you barely noticing the blade is unsheathed and cleft you in two.  Once more if you stick to acoustic, no artificial sounds and its superb.  For classical it is staggeringly good and it is something every potential audiophile ought to hear if not possess.  However be aware that its upper end while perhaps it’s Ety ER4-B like technically perfect, its ear ravaging.  You play loudness war produced stuff, cheap pop, hard abrasive stuff and it can be exhausting.  The HE-350 while a true marvel is not a can for all seasons nor all styles.  Yes it’s utterly magnificent but proceed with caution.
Value:  Just buy one.  Tbh I expect these will go second hand for more than their new price due to lack of availability.
Pro’s:  Acoustically near perfection.  Disturbingly cheap.
Con’s:  Too much upper end energy.  Can be fussy with its musical pairings.
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well the thing to keep in mind is they are audiophile tuned, even a little bright.  if someone comes to headfi thinking that their Beats are good then they will find the 350 extremely bass light.  same thing happened with the RE-0 headfi went crazy when they dropped to $100 and new users found their bass level a shock.
Thank you, a bit of light bass can be easily taken care of with a touch of eq, having an open soundstage for fine listening is a good thing.   I tend to like the top end of JBL speakers and the tonal quality of Electrovoice bottom end.  Having the extended top end and good sound staging will put you in the room.  For example, you are not going to listen to a choral arraignment on a set of DJ Mixing Headphones, which will pound the bass beats and snap on a snare and tophat is desired if not required.   Thank you for the review and followup.
Mr Rick
Mr Rick
I got my HE-350s from Massdrop a couple of days ago and have been giving them a listen on all my favorite gendres.  As a senior with age related high frequency hearing loss, I find the brightness described by many to be much to my liking.  I like to delegate each of the cans in my collection to a specific gendre. The HE-350s are towards the top of the list in the Classical music category, IMHO. They are a welcome addition to my collection and are more then worth the $99.00.


Grand Master Moe "G"….Don't crossface me, bro!
Ping Pong Champ: SF Meet (2016,2017), CanJams (London 2016, RMAF 2016, NYC 2017, SoCal 2017, RMAF 2017)
Pros: Tenacity and pinache in the upper midrange and treble areas, soundstage is surprisingly immense, solid construction
Cons: Bass has quality but not much quantity, treble may sound bright to very bright, especially upon first listen
Review: Massdrop x HIFIMAN HE350


It has been such a vibrant time in the Massdrop landscape, as they have been able to create successful collaborations with respected manufacturers.  Massdrop and AKG with their smooth sounding K7XX.  Massdrop plus Fostex with their richly immaculate TH-X00.  Enough of a success to spawn a new TH-X00 variant that contains Purpleheart earcups, and delegating the old model to a new name: the TH-X00 Mahogany, to be able to differentiate between the two models. When I had a chance to listen to the new collaboration with HIFIMAN headphone, I jumped at the chance and feel honored to be considered.  Thanks to Christian, aka @CEE TEE, for the Massdrop x HIFIMAN HE350 in exchange of my honest opinion.  Also, congratulations to his new job with Massdrop as Audiophile Custom Products Manager!  Much success to Christian and thanks to @WillBright as well, bringing those who purchase Massdrop's audiophile products along the journey with you both, one person at a time. 
According to Massdrop:
In 2010, HiFiMAN released the HE-300, HE-500, and HE-6, a series of headphones that rivaled those from the world’s most established brands and redefined price-to-performance expectations in their respective categories.  This product line solidified the still-young company’s status as one of the most respected names in the audiophile community.
Today, we’re proud to announce the Massdrop x HiFiMAN HE-350, a custom product based on the company’s entry-level HE-300, which was eventually discontinued despite being a clear favorite for many.  This model has everything you loved about the original, plus a few awesome updates made in response to feedback and requests from the community.
With regards to the drop, there are a couple of weeks left, and will cost $99.99 shipped in the United States.  International shippers can use a forwarding partner for an additional charge of $15.  Here is additional info from Massdrop with regards to international shipping (if you live outside the United States):
Note: If you're an international customer looking to partner with a shipping forwarder, please read this FAQ.  At checkout, international orders will be charged $15 for the third-party freight-forwarding service. You will need to input your shipping address as per a normal drop.
Expected ship date is August 3, 2016.
Here’s a little more info as well from Massdrop:
The HE-350 uses entirely new dynamic drivers, different from those in the HE-300, resulting in a more neutral sound signature with less distortion and more detail.  We've also improved the cable connectors and plug, and updated the frame to HiFiMAN’s latest (and much lighter) structure.  We made the headband more comfortable for those long listening sessions, and changed the colorway from black and silver to a more understated black and gray.
Best of all, we’re able to offer the HE-350 at an even more accessible price point.  How accessible?  We’re talking $99.99 shipped to your door in the United States.  Developed in collaboration with our friends at HiFiMAN, this will become the entry-level audiophile headphone recommendation.
Let’s check out the HE350 and find out if it is detailed in presentation, constructed with thought and structured materials, and if I feel this will become the entry-level audiophile headphone recommendation.  Come along the journey with me to audio bliss…
Audio equipment used in the review
Massdrop x HIFIMAN HE350: $99 Shipped in the US ($15 extra for international orders)
Headphones mentioned and compared
1MORE MK801: $79.99
Fostex x Massdrop TH-X00: $399
Grado Labs The Prestige Series SR80e: $99
HIFIMAN HE1000: $2,999
Master & Dynamic MH30: $349
Master & Dynamic MH40: $399
Puro Sound Labs BT5200: $129.99
Sennheiser HD 598: $249.95
Sennheiser Momentum 2.0 AEi: $349.99
Headphone earpads
Brainwavz Audio Headphone Memory Foam Earpads - Angled, Pleather: $26.50
HIFIMAN Leather Earpads: $20.00
Stock HIFIMAN Velour Earpads: $10.00
Modding material
Paper towel
iPhone 6 (Space Gray, 128GB):  $849.99 or $399.99 with a 2-Year Contract
Microsoft Surface Book: Starting at $1,499
Questyle Audio QP1R Golden: $899 USD
iFi Audio micro iCAN SE: $299
iFi Audio Pro iCAN: $1,695
Software applications used
Sound Level Analyzer: $4.99
Spotify Premium – Extreme Setting
TIDAL HiFi – Lossless

[size=1em]Thanks for the interest!  I have been a music aficionado since first listening to greats such as Anita Baker and Michael Jackson in their glory years.[/size]


An avid wrestler, coach, teacher and mentor, I like to immerse music lovers in headphones, earphones and sources that do nothing but make the listeners smile.
Ringing in my ears?  Oh, tinnitus?  I get that about 2 times a year, for about 10 seconds each time.  Other than that, I’m currently good to go with regards to my hearing.  Even if my hearing is perfect or not so perfect, what I hear may or may not match what you hear, for a multitude of reasons (genetic, physical, psychological, age, etcetera).
My music preferences are anything that has a great beat to it, not too vulgar in nature and anything that can induce head-bobbing, toe-tapping and maybe even dancing if the mood is right.  I normally listen to (alphabetically): Alternative, Classical, Hip-Hop, Indie, Popular/Top Hits, Rock, and R&B/Soul.  I will even from time to time listen to Blues, Jazz, Modern Electronic, Retro/Classics, and World.
Measurements - I measure headphone output dB with my decibel measurer app that anyone can download, replicate and have an instant reference with what I use to test.  Frequency spectrum measurements are seldom posted, as the manufacturer’s measurements are usually the best guidelines to go by.  Why?  They use them to tune their equipment, and it’s from their own specific parameters.  I completely agree with Ken Ball from ALO’s statement/post when it comes to frequency response measurements (verbatim):
“…I thought it might be good to post some frequency response measurements first before we see a lot of variations posted by people. Without going into a long drawn out thesis / debate on measurements I just want to say that I have not seen any reviewers measurements that are accurate and it can be difficult to interpret a freq measurement. I don't use HRTF compensation curve on my measurements because I am familiar with the raw freq curve so when I see a curve I know what it sounds like and am comfortable with what I am seeing. So to state my measurement so I can be happy that this is the official freq I am posting it here now. I do not really want to get into any debates on what the freq means or read into it too much as a freq measurement is only a very small part of the over all picture of the product. I would MUCH rather listen to the IEM than read a freq.
In addition, I dont want to sound like I dont welcome people to also have fun and measure, but just want to say that taking a accurate measurement is tricky, also tricky to read into the measurement. I spent over $15,000 on on measurement system and it took me almost a year with professional help to calibrate and set it up 100%. So in doing so it is expensive and can be difficult to set up and calibrate. I know my set up is accurate because I send my IEMs to independent labs to double check everything.”
Measurements are valid to possibly get a glimpse or gist of what we are hearing, but measurements are not the end all be all.  Various manufacturers have told me privately that even though it may measure flat, it may not sound flat.  Also, measurement devices do not equal our brain and cannot measure with absolute 100 percent certainty with regards to what we hear and feel.  I listen with my ears, and write based on my interpretations of the music that is being presented to me.
A wise man once told me: "Music is the only thing that doesn't have war, pestilence, garbage, crap - music is so general, it's such a beautiful canopy of peace."
First listen
When I received the HE350, I went through a brief listen, and then connected it to various sources to burn in the headphone.  I normally burn in all of my earphones and headphones I receive, but I really wanted to hear if there were changes through this particular model.  More about this later.
Build and aesthetics
HE350, HE350 connected to QP1R
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HE350 velour earpad, i
nside of HE350 headband​
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HE350 side view
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HE350 connector socket, 
HE350 earpad off of earcup​
IMG_5701.jpg  IMG_5671.jpg  ​
HE350 earcup and earpad
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HE350 - right and left sides
IMG_5687.jpg  IMG_5698.jpg
The glossy black frame of the headband is built very well and the black headband itself is tastefully created with contrasting white embroidery, using stitching to hold the slight padding of the headband intact.  The headband mechanism offers five settings; a rather tight fit from its furthest down setting, on up to a very generous fit for the largest of heads with its fifth and highest up setting.  A large “H” shows the HIFIMAN logo at the ends of the headband, and the top of the yokes show “HE350” on the left and right of the headphone.  The yokes are made out of plastic, but has a satisfying solid feel and matte look to them.  The earcups have a gunmetal look, and have a fine-looking gloss to them as well.  The grills are glossy black, and are see through just enough to see a little bit of the inner workings of the headphone.  The earpads are black velour and look to be of high quality.  The cable connectors of the HE350 look to be of high quality, as do the black 53-inch cable with right angled plug.  This headphone might as well be called the Batman because of its mostly slick gunmetal and black appearance.
HE350 and HE1000
IMG_5703.jpg  IMG_5704.jpg
Fit and comfort
The adequately sized and lightly padded headband, velour pads, light total headphone weight, coupled with a better overall fit than my HIFIMAN HE1000 makes the HE350 one very comfortable headphone to wear.  The earcups rotate a full 180 degrees and pivot just over 180 degrees, meaning the HE350 provides a full range of movement for just about every type of head in existence.  The only issue that I foresee listeners having is with the velour pads.  I personally don’t have issues with it as I am used to wearing wrestling head gear that gets very hot and sweaty, but some listeners that aren’t used to the velour padding of headphones may feel that the pads will get warm or hot with extended listening sessions. 
The 53 inches of cable length is great for listeners on the go, and the fact that the HE350 offers detachable connectors standard is a welcome aspect, especially for listeners directly coming from the beautiful sounding Fostex x Massdrop TH-X00 Mahogany headphone, which has fixed cabling standard.
HE350 cable - left, HE1000 cable - right
With regards to the fit of the headphone, I personally find the most comfortable fit of the headband the second or third lowest setting.  Each setting holds rather strong, so changing to and discovering your individual setting is a joy to obtain.
Glasses and the HE350
I tried the HE350 with sunglasses to test if they feel comfortable while the HE350 is on my head.  I tested with the Oakley Offshoot, which have larger stalks than regular eyeglasses.  The HE350 puts a little pressure on the Offshoot stalks, but isn't a concern with regards to pain or anything of the sort.  Your mileage may vary, especially since different sized heads, eyeglasses, tolerance to wearing eyeglasses with headphones and other factors will all come into play.
Oakley Offshoot, HE350 on head with Offshoot
IMG_5877.jpg  IMG_5876.jpg
How to replace earpads
There are four grooves of each earpad that need to come out of the indentation of the earcup.  Once you locate one to take off (push earpad portion closest to you away from you), the rest of the earcup is very easy to take off.  To put the earpad back on, repeat the process, inserting the groove of each earpad into the indentation of the earcup.  Make sure there is no play with any part of the earpad once it’s fully on the earcup.  If there is play, you’ll need to reinsert a groove or grooves into the earcup until there is no play with any part of the earpad.
Push earpad portion closest to you away from you to take earpad groove off
IMG_5675.jpg  IMG_5677.jpg
Earpad off of earcup housing
Repeat process by inserting earpad grooves in earcup indentation
HE350 earpad replacement procedure in video form:

Disclaimer and hearing factors
The HE350 sound impressions are mainly for anyone wanting a point of reference regarding how they more or less pair with the iPhone 6, QP1R and Surface Book.  Other sources may vary slightly or greatly as the HE350 sounds different enough with these three sources to warrant mentioning.  The HE350 will have a warmer and pronounced effect in the overall bass region when pairing with the iPhone 6.  The HE350 will have a supremely detailed with slight treble and bass with extended detail when paired with the QP1R.  The HE350 will have a more balanced and natural sounding approach to its presentation when paired with the Surface Book.  For reference, the HE350 is fairly easy to drive, as a smartphone such as the iPhone doesn't take full volume for the HE350 to emit levels that can damage hearing pretty quickly. 
We all hear differently, and our experiences with regards to how our interpretation of what we hear vary greatly.  Some factors that come to mind (and not limited), are: 
Your inner ear and skull’s overall composition:
Hearing loss as we age, also known as presbycusis,
Heredity, noise trauma, dietary habits, smoking, hypertension, atherosclerosis, are other factors that affect people’s overall hearing ability.
Analyze this and that
The test tracks that I use in my reviews are located in these albums (album alphabetical order)
1989 (Deluxe Edition) by Taylor Swift (FLAC 44.1kHz/16bit)
21 by Adele (FLAC 44.1kHz/16bit)
Bad (2001 Special Edition) by Michael Jackson (FLAC 44.1kHz/16bit)
Bangerz by Miley Cyrus (MP3 320kbps/44.1kHz/16bit)
Beyoncé by Beyoncé (FLAC 44.1kHz/16bit)
good kid, m.A.A.d city by Kendrick Lamar (FLAC 44.1kHz/16bit)
Heart Blanche by Ceelo Green (MP3 320kbps/44.1kHz/16bit)
Hybrid Theory by Linkin Park (FLAC 48.0kHz/24bit)
Make Yourself by Incubus (MP3 320kbps/44.1kHz/16bit)
No. 5 Collaborations Project (EP) by Ed Sheeran (MP3 320kbps/44.1kHz/16bit)
One by One by Foo Fighters (FLAC 88.2kHz/24bit)
Random Access Memories by Daft Punk (FLAC 88.2kHz/24bit)
Schubert  Berliner Philharmoniker by Nikolaus Harnoncourt (FLAC 48.0kHz/24bit)
The Dark Side of the Moon by Pink Floyd (FLAC 44.1kHz/16bit)
Thriller by Michael Jackson (DSD 2822.4kHz/1bit)
X (Wembley Edition) by Ed Sheeran (FLAC 44.1kHz/16bit)
Several standalone tracks (track alphabetical order)
Dock of the Bay by The Persuations  A Cappella Dreams (WAV 44.1kHz/16bit)
M.O.R. by Blur  Blur 21, Blur (2012 Remaster  Special Edition) (MP3 320kbps 44.1kHz/16bit)
Schubert String Quartet No. 14 in D minor D. 810, Death and the Maiden: III. Scherzo. Allegro molto by Oslo String Quartet – The Schubert Connection (DSD 2822.4kHz/1bit)
Serenade (Spanish Dance), Op. 54, No. 2 by Jano Starker and David Popper – Wilson Audio Ultimate Reference (APE 44.1kHz/16bit)
The Peppery Man by Natalie Merchant – Leave Your Sleep (WAV 44.1kHz/16bit)
These Bones by The Fairfield Four – I Couldn't Hear Nobody Pray (WAV 44.1kHz/16bit)
If I am listening to a product that is not able to be listened with the highest resolution tracks that I have mentioned, I will listen to the TIDAL versions (FLAC).
Sound impressions
Remember earlier in the review when I said that I wanted to find out if I observed changes with burn in?  Based on the time I’ve currently burned in the headphones so far (around 125 hours) I haven’t noticed too much change as the inherent qualities of the sound have stayed more or less the same.  The HE350's sound signature produces an upper midrange and treble emphasis.  This is a bright sounding headphone.  No sugar coating in this regard.  Highly resolute, with a crisp and detailed prominence.  Midrange is slightly recessed and bass has quality but also takes a step back in quantity.  The open back nature helps create a soundstage that I feel is unrivaled at this price point.  The clarity is outstanding for a dynamic driver and exemplary, especially in the treble areas.  Some may think that the large size of the drivers (50mm) would play a part in creating more bass to the sound signature.  This is not the case with the HE350.  What I will say the size more than likely helps to convey more of a full and wide soundstage, which is a welcome effect in my book.  Will my sound impressions match yours?  Who knows, but there is no denying the fact that they are inherently bright, may be slightly sibilant at first listen, and the soundstage and quality of music that is presented is apparent.
The treble is the captain of the ship, and will be either be loved and adored for many years to come, or loathed and reviled as one of the most treble/upper midrange heavy headphones you may hear (aside from Grados).  The high frequencies are crisp and the open back creates an open and airy experience.  It really is a nice experience, especially if you want to take a detour away from pure reference or bassy sounding headphones.  If you are a lover of treble, purchase the HE350 because it will reward with oodles of treble, and probably then some.
Upper midrange, where art thou?  Yes, right here.  And there.  And seemingly everywhere.  Whew, when paired with a detailed and resolute source, the upper midrange exhibits itself with such a voracity it seems, but is toned down somewhat to my ears once a little burning in and also brain burning in comes into play.  Vocals are vibrant, rifts are obvious and guitars sound dynamic.  I can listen to the HE350 for hours without any sibilance or too-bright issues, since I have gotten used to the bright and open sound of the beautifully created headphone.
The lower frequencies can exhibit a sheer softness, but does not sound muffled – rather, it sounds articulate, yet gentle.  As you can tell by now, this is not a basshead headphone or anything near the sort.  For those that want to take a break from the bassy headphones of the world and hear adequately accurate, yet subdued in rapaciousness compared to bassier headphones, the HE350 is the one to audition.
I feel the HE350 portrays good depth of field, but excels in the soundstage width department.  The upper midrange and open back characteristics aid in creating that air, that breath; that aura, if you will.  It really is a great sound and feeling once you dial in your favorite source and music.
With regards to sound leakage, the HE350 leaks a lot of sound, as its open-back construction would be a great choice to annoy co-workers and people around you - and not a great choice if you value the peace and serenity that an alternatively chosen closed-back designed headphone inherently produces to those around them.
My wife listened to the HE350 for a few minutes listening to some tracks off of the QP1R, and I asked: "How do you like them?"  She says "It sounds fine.  It doesn't have a lot of bass, but sometimes you don't need a lot of bass."  She ends with: "It's better to sound bright than dull!"™
Here's my impressions of the HE350 in video form:

iFi Audio micro iCAN SE
The micro iCAN SE is an amp that produces a defined and resolute sound signature, especially when coupled with the QP1R.  Detail is palpable, and the micro/macro detail of the HE350 truly shines.  The "3D HolographicSound" setting helps add in a little more forward, rich and transparent sound field perception.  iFi Audio explains: "3D HolographicSound recreates a holographic sound field like listening to a pair of speakers."
Here's the 3D HolographicSound settings:
 - = Direct
●●● = 3D for flat sounding recordings.
● = 3D for recordings with excessive stereo effect.
I only need to turn the volume dial a little (to around 9 o' clock) to obtain a comfortable listening level.  The micro iCAN SE also features a Bass Boost switch, called "XBass".  iFi Audio explains: "XBass was uniquely-designed to extend the bass response to suit different headphones."
Here's the XBass settings:
- = Direct
●●● = For bass shy headphones.
● = For average bass headphones.
XBass is my favorite setting on the amp because I can immediately hear and feel a change in the bass response (increased volume of bass, texture and decay).  
At the one dot setting, I personally feel the HE350 doesn't benefit too much with this setting.  A little more bass is apparent, but is still not bassy enough to my ears, as the one dot setting is best for average bass headphones.  The HE350 is in my opinion a bass shy headphone, and would benefit the best with using the three dot setting.  With that said...
Using the three dot setting adds more volume of overall bass and on certain tracks has bass that can be heard, felt (not immensely, but sufficiently), and there is more perception of prolonged reverberation and decay.  The three dot setting doesn't turn the HE350 into a basshead headphone (at least without source EQ applied), but it turns the HE350 into more of a balanced sounding headphone.  The result of the three dot setting is creamy-smooth sounding bass that melds naturally into the highly detailed midrange and higher frequencies.
iFi Audio Pro iCAN
I wanted to try out the HE350 with a balanced amp, so I used my HE1000 balanced cable with the HE350, connected to the Pro iCAN I had on loan for a couple of weeks. My favorite settings are:
Tube+ selected ("2 x NOS GE 5670s are engaged with the J-FET circuitry switched out for an all-valve Class A operation": "Even Order harmonics dominate")
XBass selected to "40Hz" (Max Bass setting)
3D selected to "OFF" or "90/60+" (Max Loudspeaker Angle setting)
Gain set to 0dB
The Pro iCAN is connected to the QP1R as the source.  The resulting sound is utterly transparent, fluid and the smooth presentation is resounding.  Delicate, yet full of depth and dynamic in nature.  Seriously blissful sounding and truly brings out every last drop of the technical capabilities the HE350 is able to emanate.  The GE 5670 brings out the warmth of the HE350 with no inherent brightness, just a more clear view of the treble as it has been softened to seemingly refresh the senses.  Bass is fluid with adequate heft because of the "40Hz" setting.  The midrange is gentle and lush.  Soundstage and spatial capabilities?  Pretty breathtaking; natural, spacious, and transparent, in my opinion.  The combination is truly an eye opening experience.  No hype here, just sweet sounding truth to my ears. 
Gaming: Microsoft Surface Book
The HE350 performs well at least with certain genres of games that I like to play such as racing and fighting games.  The soundstage and pinpoint cues are excellent to my ears and are an easy, non sibilant listen with the Surface Book.  The below titles were observed by watching YouTube gameplay videos.
First Person Shooter
Counter Strike: Global Offensive
From the different types of gunshots, smoke screens, hand to hand (knife fighting), soundstage and sound position of all are excellent.  A joy to watch and listen to the CS:GO Cologne Grand Finals.  "Team EnVyUs" is simply relentless, with unabashed aggression.
Forza Motorsport 6 
The acceleration, shifting, screeching tire skids, braking, sliding, safety cone hitting, car to car smashing and background music are all pretty immersive, with clarity and detail.  Fantastic to listen.
Street Fighter V
Everything about listening to Street Fighter V sounded hype!  Seriously though, It isn't as though you feel each punch, kick, projectile and throw with a sheer immense bass presence, but the clear and expansive technicalities behind it all sounds delightful. 
Headphone comparisons
Before I start with the comparisons; I have listened to a lot of audio equipment, but I haven't listened to everything.  If you request a comparison and it's not listed in my profile and hasn't been reviewed, then there is a chance that either I haven't listened to it in a long while and don't want to compare by memory, or I don't have the requested product(s) with me to compare.  Consider being proactive by sending me a PM (private message), sending me the headphone(s) and/or sources, IEMs, etcetera, you would like for me to compare, and I'll add it to the review (or any review that I've written).  If you don't have the requested product(s) with you and I don't have the requested product(s) with me, chances are slim that I will be able to fulfill your request because I always like to A/B with audio equipment that's immediately on-hand.
My headphone comparisons are volume matched as close to the 0 to .1 dB discrepancy of the two A/B compared headphones as I can; to read my full method, check out the (Q15) Decibel Measurements, Disclaimer and Headphone Comparisons section in my Questyle Audio QP1R review

There is more treble emphasis from the HE350, and the MK801 has a meatier midrange with more quantity of bass.  Soundstage, layering and spatial factors all tailor to the HE350, mainly because of the open back nature compared to the closed back nature of the MK801.
Fostex x Massdrop TH-X00 (Mahogany)
The TH-X00 has much more quality and resonant bass, midbass and midrange.  The HE350 on the other hand, shines in the upper midrange, treble, and slightly edges it out in the soundstage factor due to the open back nature of the HE350.  These are two very different sounding headphones, and come down to your preferences: do you want a liquid midrange with high quality and quantity bass, then then TH-X00 is the one to get.  If you want high frequencies that seemingly bursts with auditory flavor, then the HE350 is the one to get.  Or, purchase both of them, since they are both different enough to tailor to different moods and preferences.
Grado Labs The Prestige Series SR80e
SR80e vs HE350 with Stock Velour and BAP - The fit of the SR80e is lovely, as it is very lightweight, and the foam earpads (“cushions”) are old school in nature but are nonetheless comfortable on my ears.  The SR80e is lighter than the HE350, but the HE350 feels sturdier as a whole.  The SR80e is a pretty bright sounding headphone, brighter than most headphones that I’ve listened to.  The SR80e is brighter sounding than the HE350, but not outrageously so.  There is more pronounced bass and a more in-your-face sound as a whole with the SR80e.  There is more of a V signature of the SR80e compared to the more balanced sound of the HE350.  I would even say the HE350 sounds slightly more laid back than the SR80e.  The SR80e has a dynamic sound with pretty good midbass for a lightweight and soft-feeling headphone.  The midrange is somewhat recessed compared to the treble.  The higher frequencies are vibrant compared to the HE350, and are slightly peakier in nature.  Replacing the stock velour earpads with the BAP makes the HE350 bassier and tames the treble, but is still not quite the bass quantity comparatively of the SR80e.  Soundstage of the SR80e is adequate, but is not exceeding transparent, especially when compared to the more spacious feeling of the HE350.  My take from both are that the SR80e is a more energetic sound, and the HE350 is a slightly more resolving and balanced sound.  The SR80e is a dynamically bright, yet merry sounding headphone, especially for the price.
Why am I comparing a $99 headphone to one of the top of the line headphones in the world?  Why not!  When it comes to fit, I will admit it – the HE350 has got the HE1000 beat.  The headband of the HE350 fits normal-sized heads, as the HE1000 seems to want to fit abnormally-sized heads, as evidenced by the sheer height of notches the headband can rise up!  However, when it comes to sound, the HE1000 bests the HE350 at most all areas – bass is more resounding, rich and a joy to listen to with the HE1000.  The midrange of the HE1000 is full, slightly laid back and liquid, all rolled up into one.  The treble is more apparent than the HE1000, and the soundstage is surprisingly large – not quite as large as the HE1000 – but still makes you want to give a smile when you hear and feel the soundstage physiognomies of the HE350.
Master & Dynamic MH30
The MH30 exhibits more bass and midrange than the HE350.  The HE350 emits seemingly heaps more treble than the MH30.  The HE350 and MH30 can best be described as polar opposites.  The MH30 is bassy and almost primitive in nature, and the HE350 is comparatively enveloping and transparent in the upper frequencies.
Master & Dynamic MH40
The MH40 is more towards the HE350 tonally compared to the MH30, but it’s still not quite there.  There is still a lot more bass and midrange emphasis than the HE350.  There is more treble out of the MH40 out of the MH30, but cannot hold a candle to the sharp, steely and as you listen more, smooth nature of the HE350’s treble and upper midrange.
Puro Sound Labs BT5200
This headphone is similar to the MH30, but with slightly less all out bass presence, which means there is still a lot more bass and midrange presentation compared to the HE350.  The upper midrange, treble and soundstage is where the HE350 shows its true chops, making some bassier headphones, including the BT5200, give a congratulatory bow to the presence of the brilliant nature of the HE350’s upper midrange and treble.
Sennheiser Momentum 2.0 AEi
The Momentum 2.0 AEi has more of an overall balanced sound than the HE350, with the bass emitting with more punch and slam, midrange that is more in your face, and treble that is smoothed over in the uppermost frequencies.  The HE350, and its open back nature does have a wider soundstage, enhanced imaging and crisp sounding upper midrange and treble than the Momentum 2.0 AEi.
Sennheiser HD 598
The HD 598 is lightweight and comfortable with a headband that is soft with small slots that probably allows for better airflow going around the top of your head.  At least, that's what it looks like.  It's a nice design, nonetheless.  The HE350 is comparatively larger than the HD 598, but still similar in weight and comfortable on the head.


You are going to receive more visceral bass from the HD 598 with more slam.  Quality of bass is similar, but the HD 598 deals with subbass better because of the more inherent bass rendering capabilities.  This is pretty much where the HD 598 has a clear advantage (if you value more bass) over the HE350.


The midrange of the HD 598 is grittier and less resolute than the HE350.  The HD 598's midrange is warmer, more closed in, and sounds syrupy compared to the resolute and less viscous nature of the HE350's midrange.


Moving onto the higher frequencies, there is not much comparison, at least to my ears.  The HD 598's treble rolls off much earlier than the HE350's far-reaching tendencies.


Extension, depth, crispness, coherency, transparency and perceived soundstage all favor the HE350 when it comes to treble comparisons.  Layering and separation of not only various instruments, but vocal presence favors the HE350.  Treble presentation, soundstage perception, and other intricacies are areas where the HE350 will most likely have over a lot of headphones, at least in its $100 price range.


Overall, the HD 598 emits a decent sound with adequate bass, and the HE350 emits a more micro and macro detailed, and harmonious sound than the HD 598 to my ears.  Using the BAP, bass is bumped up and sounds not very far off from the bass of the HD 598, but wouldn't argue that either or can be perceived as more when connecting to various sources.  Overall sound signature, depth, balance and resonance are enhanced as well with the BAP compared to the stock pads, which makes the disparity between the two headphones a little bit wider, in my opinion. 



All of the headphones compared are amazing sounding, and are prodigious in their own manner, regardless of form factor (closed/open back) and price ranges relative to the HE350, especially when paired with a favorite source.

Pro iCAN and balanced HE350
Should you modify?
It’s really up to you.  By now you should know that having this headphone as part of your collection (or only headphone) that it is an upper midrange and treble deity.  With that said, you may want to dial in modifications to help bring out the bass as well as taming down the treble in the process.  What can you do? 
  • EQ – use your source’s EQ settings to dial in a preferable frequency response to your ears.
  • Bass Boost or equivalent – use your source’s Bass Boost or equivalent button or switch, as you can with a button press or flip of a switch have immediate results with increased bass with the expense of probably lower perceived treble - which is what you want anyways, right?
  • Earpad change – changing the earpads may change the frequency response to one that sounds better to your ears.
  • Third-party elemental cables – copper, SPC, silver/gold or silver litz, etc. may help further refine the sound signature of the HE350.
  • Physical modifications (be careful and focus on reversible mods first!) such as changing the grill, adding foam, felt, different materials and densities can make for a very fun project to help create the sound that ends up sounding utterly amazing.
I personally won’t be modifying as I am thoroughly enjoying the unique sound signature the HE350 produces, but would like to hear upcoming modified HE350s at future meets when people may bring them in tow.  I take that back: I purchased a couple of earpads, now use the Brainwavs Headphone Angled Memory Foam Earpads – Angled, Pleather, and found adding material helps tame the treble and increase bass.
Meeting of the musical minds
The Source AV Design Group is a location in Torrance, California, where you can listen to lower to high priced headphones and amplifiers, on up to multi hundred-thousand-dollar speaker systems.  Their showrooms are positively ridiculous, with one in particular sounding better and more visceral than some dedicated movie theaters! 
I attended the first of many Summer Series events at the location, the link to the events thread is here:  I brought some gear to the meet, and wanted to obtain a few impressions from my friends, most of which are Head-Fi members. 
Overall impressions: Most all who listened thought the treble came off as bright sounding, and one said they thought there were issues in the treble area.  All said for the price, the sound is great.  @Bones1885 says “for the money they are damn good.  Some stuff comes off a little sparkly, but for the money, hey?”  @Gilly87 also says he can’t think of any headphones up to the $300 range that can even touch the HE350 (especially after the modifications were implemented).  An argument/debate ensued, and I think the HE350 held its own.
Earpad synergy
Speaking of modifications, @Netforce brought his Brainwavz Headphone Memory Foam Earpads – Angled, Pleather to try.  In order to use it with the HE350, you are going to need to either use the earpad rings from the stock velour pads, or purchase a HIFIMAN set of pads and then use the rings from those to put in the Brainwavz Angled Pleather (I’m going to call them BAP from now on) pads.  I asked @Netforce why he chose specifically the BAP pads.  He said because he wanted a compromise between the large Alpha pads and small Focus pads that he didn’t really enjoy with his HIFIMAN headphones.  I am used to the pleather TH-X00 angled pads, so I felt right at home with the BAP and HE350 on my head.  After all is said and done, I purchased the BAP as well as the stock HIFIMAN leather pads (stock on HE-500 and HE-6 headphones [source, HIFIMAN’s online store]) for myself, and will be using the BAP as my main HE350 earpads. 
The BAP and HE350
IMG_6003.jpg  IMG_6007.jpg
BAP dimensions - left/top, BAP top plus side views - right/down
BAPdimensions.jpg  BAP.jpg
HIFMAN leather earpad dimensions (photos below)​
Inner Diameter: Approx. 59 mm/ 2.32 in 
Outer Diameter: Approx. 105 mm/ 4.13 in 
Thickness: 24 mm/ 0.94 in 
Weight (pair): 33.8g/ 1.19 Oz/ 0.07 lb
HIFIMANleatherpads.jpg  HIFIMANleatherpads2.jpg
Earpad replacements


I received the BAP and HIFIMAN leather (pleather) earpads, and both are great in their own way.


BAP to the left side, and HIFIMAN leather earpads to the right side
IMG_6174.jpg  IMG_6179.jpg
BAP and HIFIMAN leather earpads
IMG_6177.jpg  IMG_6178.jpg
BAP side view
Stock velour earpads and HIFIMAN leather earpads
IMG_6186.jpg  IMG_6187.jpg
Stock velour earpad on the left and HIFIMAN leather earpad on the right
IMG_6189.jpg  IMG_6190.jpg
HIFIMAN leather earpads
IMG_6191.jpg  IMG_6192.jpg
The HIFIMAN leather earpads are great if you want the same size and fit as the stock velour pads, but want a leathery feel instead of the velour of the stock pads.  Bass is improved just a tad, not very much, but feels better to my ears than the stock velour pads.
Moving onto the BAP, I took out the rings of the HIFMAN leather pads and put them in the BAP, which comes with no rings, only the earpads themselves.  Here’s the process:
Installation: looks like it can't be done, but it can!
IMG_6193.jpg  IMG_6194.jpg
Nice and easy, slowly easing in the ring, stretching/moving the earpad material as you insert more ring inside the earpad material
IMG_6195.jpg  IMG_6196.jpg
Keep moving the ring inside slowly as to not damage the earpad material
Make sure everything is nice and smooth inside and out
BAP installation finished
BAP: Without ring on left, and with ring on right
BAPs all finished - the BAP replacement should take a couple of minutes until it comes out looking great
Bass is more improved than the stock velour pads and the HIFIMAN leather pads to my ears, and puts the earcups at an angle on your head as well due to the angled nature of the BAP.  Some may be happy with just the earpad change, as the treble doesn’t sound as peaky to my ears compared to the stock velour pads.


In athletic (and other categories) terms, I would say the HIFIMAN leather pads would be an intermediate replacement (material change), and the BAP would be an advanced replacement (material and earcup angle change).  


My favorite is the BAP, since bass is improved, treble is slightly less peaky, and the overall sound is more to my preferences in comparison to the stock velour pads and HIFIMAN leather.



An observation
After my wife listened to some music from my iPhone 6 and the HE350 with BAP only, she said it makes the Formation by Beyoncé song have a different type of presentation.  I asked "What do you mean?" She replies "The headphones make it sound better than what you would normally hear on the radio."  I said "Pretty nice sound that's coming out of this headphone, only $99 shipped for those who purchase it".  She said "Really?  That's great, I thought for sure this was one of your more higher-priced headphones!"  She listens to the HE350 again later in the day (Dock of the Bay by The Persuations – A Cappella Dreams) and says "This is a really good sounding headphone!  Only $99? (smiles)"

It’s all about the ply!™
The BAP helps to bring out the bass just a tad, but was still a little bright to my tastes.  That’s when @Netforce brings out paper towels (looks like the Bounty brand) and proceeds to stuff them in the earcups of the HE350.
@Netforce installing Bounty paper towel
IMG_6004.jpg  IMG_6006.jpg
Here’s a video of @Netforce explaining the modification of my HE350:

The impressions regarding the paper towels are based on the use of specifically the BAP.
@Netforce originally used 4 ply (Bounty paper towel folded twice) and placed in the earcups.  Treble subsided, bass improved, but may have had an overall less clear sound as a result.
Then I suggested only using one ply (Bounty paper towel, not folded) and placed in the earcups.  My favorite sound of the different combinations.  Bass improved but wasn’t muddied, treble subsided just enough to not sound too bright, and depending upon source, can emit acceptable levels of bass as well.
@warrenpchi suggested a perforation of the paper towel, where there is around an inch diameter of paper towel from the earpads and a perforated hole in the middle of the paper towel, to allow the unobstructed sound of the HE350 to emit.  I found it still tonally a little bright because there wasn’t as much material to modify the overall sound, but is a painless modification that may be preferred to your ears.
@warrenpchi listening with focus - left/top, and his perforated mod, implemented by @Netforce - right/down
IMG_6010.jpg  IMG_6012.jpg
To summarize in alphabetical order:
@moedawg140 mod: BAP and 1 ply Bounty/material
@Netforce mod: BAP and 4 ply Bounty/material
@warrenpchi mod: perforated/hole in middle material
Here’s @Netforce’s impressions (verbatim):
“$99 open back dynamic from hifiman and massdrop? Personally as a big hifiman planar guy hearing this dynamic open back was in my opinion nice. For the price and the clarity it is nice contender for probably the best value can at $99. As it is stock pads and through my fiio x5 my first desire like with a lot of my headphones was to try it with an amp so I hooked it up with my Topping X1 amp and we got a nice improvement to the bass. Treble I found in a bit bright.
After listening to it stock and passing it around so others could listen to it I decided to take my angled brainwavz pads and put them on the headphones and holy moly we got an improvement to the bass! For the treble I did some experiments with some paper towels and tried adding some to tame the treble, initially 4 pieces was a touch too veiled, 1 piece seemed like it was what most people preferred! Did a little quarter size hole mod and that wasn't as well received. So overall with like most hifiman cans modding was a lot of fun and simple!”
Here's @Gilly87's impressions (verbatim):
"Stock, I'd say they are not a bad buy at $99 - reminded me of a less detailed version of my Beyer T90s with stock pads with mediocre extension. I could see some folks liking it, and it's not a bad buy at $99.
Now, @moedawg140 , @Netforce , and a few other guys at the show were working on a mod using different pads and putting different materials between the driver and ear, and I have to say, I was pretty impressed by the outcome - they sounded like the best warm, bassy headphones I'd ever heard under $200-$300 USD. If Hifiman could replicate the effect and make it look classy, they'd have a headphone that could easily convert the Beats crowd towards more upmarket stuff. Really nice.
If you like to tinker with pads and mods, these could be a dream come true, and either way they're a bargain at $99 for sure."

Remember the person who listened to the HE350 stock saying that there were issues in the treble? After the BAP and material mod, he exudes "This sounds like a completely different headphone now!  I like it!"
I would suggest, if you like the feel of pleather and angled-type pads, to give the BAP a try.  Even if you don’t purchase 3rd party pads, you can for very cheap or free use paper, a paper towel, shelf liner - anything permeable, to dial in the best sound to your ears.
Cultivate a fresh sound
What does this mean?  Too often we focus on only the music we are accustomed to.  I am usually this way as well.  Here’s an opportunity to listen to something you either may not normally listen to, or haven’t heard of.  As I publish reviews in the future, I will have new and older tracks from various genres that I’ve listened to in this section, and will be largely based on what songs really moved me in particular to the reviewed product I’ve listened to on it.  Even though the tracks will be linked to YouTube videos or audio-only versions, the tracks will either be listened solely from the iPhone 6 and TIDAL HiFi - Lossless, or from my Microsoft Surface Book and TIDAL HiFi - Lossless.  Instead of describing each track in immense detail, you can simply listen for yourself and bask in the beautiful music you may have just found for the first time right now!  What’s also great is that you can come back here just to listen to the tracks mentioned!  If you have any personal issues with any tracks posted, please PM me and I'll replace it with another track.  It's all about positivity in our musical journey.  With those kind words of encouragement, here we go…
Can't Stop The Feeling by Justin Timberlake

Sunshine by Eric Benet

Beethoven's 5 Secrets - OneRepublic (Cello/Orchestral Cover) by ThePianoGuys

Easy Lover (Phil Collins & Philip Bailey Cover) by Panama Wedding & Great Good Fine Ok 

Is the HE350 worth it?
In one word, yes!  You get exemplary sound and presentation of space for not a lot of vittles, money, dinero, moolah, mazuma, whatever you want to call it - that are needed to be exchanged.  The HE350 offers amazing fit and feel of a headphone regardless of the price point, and a headphone that I personally feel many people are going to enjoy, especially when they listen to the headphone for a while and enjoy the unique sound it produces to the senses.
Final thoughts
Masssdrop and HIFIMAN have been able to accomplish the unthinkable, which is to create a headphone that checks all of the auditory and practical boxes: fit, sound, and that slick aesthetic flair this headphone manages to exude.  After thoroughly listening to and enjoying the HE350, I would agree that it should be recommended as one of, it not, the entry-level audiophile headphone.  With that said, if you want an energetic headphone that offers remarkable clarity, soundstage that is immense in diligence and a fit with feel that is above its weight in gold, the Massdrop x HIFIMAN HE350 should be a part of your personal collection.
  1. Massdrop x HIFIMAN
  2. Driver: 50 mm dynamic
  3. Impedance: 50 ohm
  4. Sensitivity: 93 dB at 1 mW
  5. Frequency response: 15 Hz – 22 kHz
  6. Velour ear pads
  7. Detachable cable
  8. Cable length: 53 in (135 cm)
  9. Cup connectors: 0.1 in (2.5 mm)
  10. Plug: ⅛ in (3.5 mm)
  11. Weight, with cable: 12.1 oz (343 g)
  12. Weight, without cable: 10.6 oz (301 g)
chicken beer
chicken beer
Actually, there's a neater way to do the mod: cut letter paper to circles, put it behind the earpad ring, it's more stable and more flat.
Thank you for the Grado SR80 comparison. That was very helpful!
How is the bass quality with the BAP pads? Does it sound bloated at all, or is it tighter, faster, or anything else worth mentioning?
The stock HE-350 is currently my favorite headphones of the 10 or so headphones I have/had in the $100-300 range. That said, I like the way the highs are but wouldn't mind a bit more punch in the bass. However, I really didn't like how AKG added bass to their headphones by swapping pads. The AKG Q701 was my favorite headphones for quite a few years (before I got the HE-350), but I did not like the sound of the 7XX nearly as much since the bass with memory foam pads just didn't sound as clean and tight as it was on the Q701.