Sennheiser HD 599

Sources split on the same hump. A majority hears a full, punchy, deep-for-an-open-back bass that Headfonia, MajorHiFi and many owners call the fun of the headphone; a large minority — RTINGS, SoundGuys, several Head-Fi reviewers and the sharper Reddit critics — hears the 100–400 Hz lift as boxy, bloated or loose, sitting in the 'mud' region rather than the sub-bass. Both camps agree the lowest octave is missing, that it distorts if you EQ the sub-bass up, and that a high-impedance or weak output makes it worse.

Sources split: three quarters by weight hear rich, present, musical vocals — RTINGS, Headfonia, SoundGuys and most owners — while a quarter hears a lower midrange thickened by the hump and upper mids set back, so male voices turn nasal or boxy and singers sit 'in the next room'. Several on both sides note that it flatters poor recordings and that the 1.5–2.5 kHz dip is what reads as either smoothness or veil.

Smooth, soft and non-fatiguing is the majority read — Headfonia, DIY-Audio-Heaven, Thememefactory7 and most owners agree it never gets sibilant. A minority hears it as lacking air and extension above 10 kHz (SoundGuys, HiFi Oasis) or as slightly grainy and, on some units and sources, shrill around 4–6 kHz (TeoTB, angelmf2704, the ASR thread). MajorHiFi alone found it rich enough to 'verge on piercing' with strings.

“Treble is smooth and energetic at the same time. It might not be the most detailed or furthest extended but it’s musical and dynamic”

Lieven, Headfonia

“Treble is ‘soft’ and sounds pleasant. It is never harsh nor sibilant but is not as ‘refined’ as that of the HD650.”

Solderdude, DIY-Audio-Heaven

“the exaggerated low-mids and bass can make that added treble clarity and detail get lost, especially above 10kHz.”

Jasper Lastoria, SoundGuys

“The 599 has a pleasant sound but the sounds lack purity, there are colorations and the treble is granular.”

MentalFlexibility, r/headphones

Sources split on what the same tilt is. Two thirds by weight call it warm, smooth, musical and well-balanced — RTINGS 'slightly warm and smooth but well-balanced overall', DIY-Audio-Heaven 'a warmish type of neutral', Headfonia, HiWire and the Amazon majority. A third hears the hump as the flaw that defines it — SoundGuys' 'sizeable volume bump', Head-Fi's 1.5- and 3-star reviewers, ASR's 'one wide midrange' and Reddit's 'you'll understand why people hate them'. Almost everyone in both camps agrees EQ (oratory1990's preset is the usual fix) closes most of the gap.

Open and spacious for the price is the majority verdict — RTINGS' 'open, spacious-seeming soundstage', Headfonia's 'spacious and airy', HiWire, angelmf2704 ('wide and deep, better than HD 600 family') and the gaming crowd. A steady minority calls it modest or in-your-head: Leonarfd-style Head-Fi reviewers FinHifi and LinkPro, MajorHiFi ('lacks the kind of depth'), DIY-Audio-Heaven ('lacks a bit in open-ness') and one owner who found the HD 598 wider.

“Their open-back design helps to create an open, spacious-seeming soundstage.”

RTINGS

“The sound stage for an open design is good but it’s not as good as the HD6XX series.”

Lieven, Headfonia

“Soundstage Small, not IEM small tough, but notacibly smaller than adx5k i owned.”

FinHifi, Head-Fi showcase review (4/5)

“The soundstage on the HD 599 sports some decent placement, but lacks the kind of depth we’ve seen with the HD 600.”

Carroll Moore, MajorHiFi

Precise for the class and the reason it keeps being recommended for games — Thememefactory7 'spot on', angelmf2704 'very precise', HiWire and Reddit's gaming owners agree. The dissent is a gamer who found the SHP9500's brighter presentation more revealing of footsteps, and two owners with a channel imbalance on their unit.

“Imaging is also spot on, it is extremely accurate. This would be a great gaming headphone.”

Thememefactory7, r/headphones review

“First off, imaging is very precise and you can notice different layers and air among instruments. On the other hand, soundstage is both wide and deep, better than HD 600 family.”

angelmf2704, Head-Fi showcase review (3.5/5)

“That upper bass boost is god tier for hearing footsteps, and the relaxed sound let's you turn up the volume without piercing your ears.”

ThisCupIsPurple, r/headphones

“I'm incredibly disappointed!, not because they are bad by any means, but ppl hype things too much sometimes.”

Tks1991, r/headphones (vs Philips SHP9500 for gaming)

Adequate, not a strength: the centre of the record is 'enough detail to sound like a good product', with Headfonia, RTINGS and MajorHiFi calling it decent and Thememefactory7 noting the warmth hides some of it. A firm minority — thejtl against the HD 600 and SR80, Hark01, hvalle, the ASR posters — calls the resolution mediocre or muddy, and owners who moved to the HD 560S or HD 600 rarely come back for detail.

“this headphone is genuinely the warmest open back headphone I’ve ever heard.”

Thememefactory7, r/headphones review

“The warmth hides some detail however, and they are not as detailed as 6XX from my experience.”

Thememefactory7, r/headphones review

“Resolution, unfortunately is mediocre. It's not on the HD6xx nor HD560S level, but it's the best of the rest of the HD5xx series.”

Hark01, Head-Fi showcase review (2.5/5)

“The HD600 sounds faster and goes deeper and wider. It’s a more neutrally tuned headphone that wins in technicalities, speed, attack, detail and basically everything. The HD599 is warmer and smoother, more relaxed.”

Lieven, Headfonia

“The HD599 doesn’t have any real ‘flaws’. There is a bit too much warmth for hi-fi aficionados but at the same time it does not excel in anything either.”

Solderdude, DIY-Audio-Heaven

Punchy and lively for most owners — MRK1 'they dig really deep', PaulCoddington 'lively and musically involving', the footstep crowd — with the measurement side calling it 'mellow' rather than dynamic (DIY-Audio-Heaven's step response shows 'a slight lack of speed'), Headfonia docking it only for speed, and everyone agreeing it collapses into distortion if you EQ the sub-bass up. Several owners say it firms up noticeably with a low-impedance amp.

“If I have to say one less good thing about it, it would be its speed but only because I’m used to higher end headphones.”

Lieven, Headfonia

“The overall tonal balance is a ‘warmish’ type of ‘neutral’. This makes the HD599 not super ‘dynamic’ sounding but rather ‘mellow’.”

Solderdude, DIY-Audio-Heaven

“These headphones are absolutely terrible at taking a boost to any bass frequencies below 80 HZ.”

Thememefactory7, r/headphones review

“Not just clear and punchy, but lively and musically involving.”

PaulCoddington, r/headphones

The one thing every source agrees on, and the most-repeated line in the record: light, velour, low clamp, wearable for hours and in summer — 'the most comfortable headphone I've ever used' appears in some form in a dozen reviews, and even the 1.5-star Head-Fi reviewer gives it the point. The only dissent is one owner who found the clamp tighter than advertised and a few who note the velour pads flatten after two or three years.

“For casual listening at home, it's difficult to beat the comfort of the Sennheiser HD 599 for long sessions.”

Jasper Lastoria, SoundGuys

“This is without a doubt the most comfortable headphone I’ve ever used.”

Thememefactory7, r/headphones review

“They're so comfortable you will literally forget you are wearing them, and they can last a lifetime.”

Audrey_spino, r/headphones

“With several hours of listening now under my belt, I find the clamping force to be much higher than expected.”

Thomasr, Head-Fi

Light, all-plastic and generally durable — many owners report five- to twenty-year-old HD 5-series pairs still working, the pads and cables are replaceable, and the headband is padded. The caveats are consistent: it feels cheap next to the HD 600 series, the pleather headband can tear, the locking 2.5 mm socket limits aftermarket cables, two owners report a channel imbalance, and one owner's five-unit sample suggests unit-to-unit variation.

“The HD 599 is a great starter headphone and possibly an even better endgame headphone for music lovers.”

HiWire, Head-Fi showcase review (4/5, five-year retrospective)

“Yeah out of the box their sound is fairly mediocre, and I don't know how common it is but mine have a noticeable channel imbalance. But after EQ, I actually prefer them over the 560s.”

polishedcooter, r/headphones

“I went through 5 pairs of these and there are basically two types of tunning - one with wide soundstage, but somewhat boomy looser mellow bass almost identical headphone to 598 with same level of midbass hump”

GoodBoy, Head-Fi

“Not sure where the idea that there's two different sounding versions of these even comes from? As far as I know there is nothing to back this up except someone just saying it.”

Nirvana Woman, Head-Fi

None, by design: it is a fully open headphone that leaks as much as it lets in. Every source that mentions it says so, and Amazon's only negative-majority topic is 'noise cancellation' (30 positive, 55 negative) from buyers who expected some.

“Its open-back design offers almost no isolation and limits where you can use it.”

Jasper Lastoria, SoundGuys

Sources split on the price it is judged at. At the $100–150 it usually sells for, RTINGS, Headfonia, HiWire and most owners call it a bargain and a better buy than the HD 600 for casual use. Against its $200–240 list, a quarter by weight — hvalle, angelmf2704, thejtl, the HD 560S converts — say it is not worth it and that the 560S, HD 58X or FiiO FT1 do more for similar money. Nearly everyone agrees the answer changes with the day's price.