By aspect — in detail
Tonality
Contested · 10 srcSources split, and the split tracks method more than taste: everyone who has listened calls it natural, fuller and more agreeable than the MM-500 — bottom-weighted, mid-forward around 1 kHz, softer through the presence region, several calling it 'flat' or 'balanced' — while a loud minority working from Audeze's published curve reads the same shape as a 1 kHz bump over under-shot ear gain and an uneven treble, and calls it a return to the honky old house sound. The listeners hold most of the weight; the graph-readers hold the graph.
Measured
Audeze's own published response (compensation not stated): relative to 200 Hz the trace rises ~3 dB by 30 Hz, sits ~5 dB up at 1 kHz, dips at 1.8 kHz, peaks ~3.5 dB over 1 kHz at 3 kHz, then notches near 5.5 kHz and 10–12 kHz. Audeze's Peter James (MusicTech): the MM-500's forward upper mids 'have been levelled off'.
⚠ vs. listeners — The graph is the same for both camps; they disagree on what it means. Reviewers who wore it describe the 1 kHz/2–4 kHz shape as 'fuller' and 'less shouty'; the forum readers describe it as 'honk' and 'negative ear gain'. One owner's per-unit measurement from Audeze did not match the site graph, so how far the published curve represents a given unit is itself unsettled.
Where it splits
natural, fuller and more agreeable than the MM-500 (in the ear)84%
“The resulting tonal profile is what I would describe as bottom-weighted with a stronger fundamental frequency emphasis, creating a fuller, more rounded, smoother, and agreeable sound signature.”
Headfonics (Marcus)
an odd curve — 1 kHz bump, recessed ear gain, uneven treble (on paper)16%
“FR looks terrible and Im saying that as a classic Audeze enjoyer. Not sure who this is for.”
u/aceCrasher, r/headphones
Mostly agreed and mostly praised: SLAM gives the MM-520 a deeper, tighter, more textured low end than the MM-500 — 'meat on its bones', 'a more solid foundation', 'the best sub-bass response' in a planar. The two dissents pull in opposite directions, which is why this is not a clean split: one pro-audio reviewer found the lows predominant enough to trim by EQ, while a consumer-side reviewer found the bass tight and analytical but short on punch.
“The low-end now has some meat on its bones that the MM-500 lacked.”
Headfonics (Marcus)
“A controlled bass tone that puts just enough emphasis in its sub-bass to give the lows a more solid foundation.”
Major HiFi (Alex Schiffer)
“The MM-520's frequency response is boosted at low frequencies, which are predominant.”
Audiofader (Luca Pilla)
“The bass is tight, analytical, and well-defined all the way into the lowest frequencies, but it lacks the punch and impact many people associate with a fun listening experience.”
Notebookcheck (Christian Hintze)
Measured
Audeze's published trace rises ~3 dB from 200 Hz to 30 Hz with no shelf step; the maker says it tuned 'a better bass extension rather than a bass shelf'. Spec: 5 Hz–50 kHz, THD <0.1 % at 100 dB SPL.
Sources split — this is the MM-520's defining argument. The larger camp, nearly every hands-on source, hears the softened 2–4 kHz region as the fix the MM-500 needed: vocals fuller and less pointed, no shout, more organic and easier over long sessions. The smaller camp says the MM-500's midrange was its best asset and the MM-520 gives it away — either as a 1 kHz 'honk' over recessed presence (the graph-readers) or as a flatter, more clinical midrange with less warmth than before (one editorial voice).
Measured
On Audeze's graph the 500 Hz–1 kHz region sits ~4–5 dB above 200 Hz and the 3 kHz peak reaches only ~3.5 dB over 1 kHz. Headfonics, comparing against the MM-500, reads the MM-520's 500 Hz–1 kHz as 'significantly more gain' and its 2–5 kHz as 'significantly less'.
⚠ vs. listeners — Same shape, opposite verdicts: Headfonics hears the extra 1 kHz as fulsome vocals and the quieter presence as an 'antidote' to the original's shout; Reddit hears '1khz goose HONK' and 'negative ear gain'; Major HiFi hears neither warmth nor honk but a flatter, more clinical midrange.
Where it splits
smoother, fuller, less shouty — the MM-500's edge sanded off74%
“The lack of upper-mid boost reduces the ‘in-your-face’ quality of the original, so percussion is weighty but not as spiky, vocals are fulsome but less pointed with lower levels of tonal contrast.”
Headfonics (Marcus)
a step back — the MM-500's standout mids traded for a 1 kHz bump or a plainer, clinical voicing26%
“That is a pretty big downgrade in regards to the midrange.”
u/dagot23, r/headphones
Sources split: the larger camp hears a relaxed lower treble — smooth, never harsh, with only a small lift around 10 kHz for air, and to some ears a little rolled-off or dark next to brighter headphones. The smaller camp hears it as airy and clean, with cymbals that ring out naturally and even a slight tinge of brightness. Nobody calls it sibilant or peaky; the disagreement is about how much air is left.
Measured
Audeze's trace shows notches of roughly -9 dB (vs 1 kHz) at 5.5 kHz and -10 dB across 10–12 kHz, with a recovery to ~0 dB at 8 kHz and a smaller one near 14–15 kHz — the 'picket fence' the graph-readers mock. Audiofader added a +2.1 dB shelf from 4.7 kHz 'to give a little more breath'.
⚠ vs. listeners — The dips support 'relaxed'; the 8 kHz and 14 kHz recoveries are where the 'airy' camp finds its sparkle. Which one you hear appears to depend on what you came from — Focal/Grado/HD 600 owners say rolled-off, LCD-5s owners say brighter.
Where it splits
relaxed / a touch rolled-off — smooth, but not the last word in air60%
“The lower treble is somewhat relaxed, though I do hear a bump around 10k that provides a subtle level of height and air that might be immediately obvious.”
Headfonics (Marcus)
Soundstage
Contested · 8 srcSources split, and the split tracks reference frame. Reviewers comparing it with the MM-500 and other Audezes call the stage compact, near-field and 'studio-sized' — organised rather than wide. Reviewers and owners arriving from consumer, closed-back or dynamic headphones call it wide, spacious and, in one pro-audio review, unusually three-dimensional, with height as well as width. Both agree the stage gained depth over the MM-500.
Where it splits
wide, spacious, even three-dimensional56%
“The MM-520s immediately demonstrated a characteristic that had never been appreciated in headphones: the sounds also have a vertical distribution (from the center of the head downwards) with a three-dimensionality that we have never heard on other headphones.”
Audiofader (Luca Pilla)
compact and near-field — precise, not wide44%
“Now, I will not describe the MM-520 soundstage as huge; it still has a ‘studio’ or small dance hall feel to its sizing.”
Headfonics (Marcus)
Imaging
Strong consensus · 7 srcThe strongest point of agreement: pinpoint placement, clean separation and layered depth that several sources single out as the MM-520's biggest gain over the MM-500 — 'vastly superior', 'razor-sharp', 'highly localized'. Even the compact-stage camp concedes the imaging inside that stage is exceptional.
“The one difference I was not expecting was the imaging performance from the MM-520. It’s vastly superior to the MM-500.”
Headfonics (Marcus)
“the sound is highly localized with pinpoint positioning”
Major HiFi (Alex Schiffer)
“It’s not a wide sounding headphone, but the imaging especially on the sides are larger and in more detail.”
GoobVibrations210, Head-Fi (owns both MM-500 and MM-520)
Detail
Strong consensus · 9 srcBroad agreement on high resolution that stays clear without turning harsh — micro-detail audible at low volume, reverb tails and room ambience exposed, mix flaws revealed. The one relative caveat is the flagship comparison: the LCD-5s still pulls out the last bit of micro-detail.
“Where the Audeze MM-520s leave monitors behind is in the microdetails that can be heard even at low volumes: nothing escapes even at low amplification levels”
Audiofader (Luca Pilla)
“It's remarkable how clear the Audeze MM-520 sounds without ever becoming harsh.”
Notebookcheck (Christian Hintze)
Mostly agreed: SLAM adds real weight, tactility and transient snap in the low end — 'punch and weight', 'very present transients', 'more power from the MM-520'. A minority hears the same bass as tight but not impactful, with a mid-bass that doesn't hit hard; Headfonics adds that the slam scales noticeably with amplifier headroom despite the easy load.
“SLAM makes the headphone much more tactile, and things feel like they have more of an appropriate amount of punch and weight which makes them more engaging and more speaker like.”
GoobVibrations210, Head-Fi (owns both MM-500 and MM-520)
“The mid-bass doesn’t hit you with any great impact, but its transient response is still fast and tight.”
Major HiFi (Alex Schiffer)
Measured
Spec: 18 Ω, 102 dB/mW, minimum power >100 mW — easy to drive, yet Headfonics found dynamic range and low-end impact 'a lot more convincing the more headroom you add'.
Mostly agreed on 'heavy, but wearable': 555 g is 60 g more than the MM-500 and every source names it, yet nearly everyone who wore it reports the thicker memory-foam pads, leather strap and lighter clamp disperse the load well — several call it more comfortable than the MM-500, one notes pad heat over long sessions. The dissent comes largely from people who ruled it out on the spec sheet: for them half a kilo is a deal-breaker regardless of how it distributes.
“Despite the 555g weight, the MM-520 does not present an unmanageable proposition on my head.”
Headfonics (Marcus)
“Comfort on the 520 was much better for me than with the MM500, also better than with the LCD3 I tested last week”
plakat, Head-Fi (week-long loan)
“The weight is significant: over half a kilo on the head, they're a challenge: wearing them makes you feel the weight, but after about ten minutes, the feeling passes”
Audiofader (Luca Pilla)
“Now if only they'd stop fabricating these things out of lead bricks so they could actually be worn for any length of time, I'd be pretty interested in trying an Audeze can again!”
klardotsh, Head-Fi
Measured
555 g (maker spec) — 60 g up on the MM-500's 495 g; SLAM ring plus eight pad magnets per side.
Broadly praised — anodized aluminium and spring steel, a Pelican-style hard case, a quiet braided cable with mini-XLRs, and the magnetically attached pads that every source welcomes as long overdue. The asterisk is inherited: MM-500 owners reported chipping anodizing on the yokes and rings, and Headfonics notes Audeze has not said whether the finish was changed.
“When it comes to build quality, Audeze spares no expense: the housing, headband, and yoke are made of anodized aluminum and spring steel.”
Trance_Gott, Head-Fi showcase review
“The construction is impeccable”
Audiofader (Luca Pilla)
“There has been no mention of whether the aluminum rings have been treated differently to prevent the peeling that some owners observed over the years.”
Headfonics (Marcus)
Isolation
Moderate · 2 srcOpen-back by design — no isolation to speak of and it leaks. The e-drum reviewer heard every metal cymbal 'clack' through them; an owner reports the bleed is negligible at sensible levels, though not enough to track vocals in the same room with a mic.
“The first caution, as previously mentioned, is the limited sound isolation.”
digitalDrummer (Allan Leibowitz)
“For those worried about bleed from the open backs, if you’re not blasting them, it’s really pretty negligible.”
Devin, Audeze store owner review
Sources split. The larger camp sees a working reference that keeps the MM-500's price while adding SLAM, magnetic pads and better imaging — and, for audiophiles, a 'mini LCD-5s' at well under half the flagship's price. The smaller camp says $1,699 is a lot for a curve they distrust, that the average listener may prefer cheaper, less neutral headphones, and that MM-500 owners have little reason to move — a point Marroquin himself makes.
Where it splits
worth it — the MM-500's price, more headphone; a mini LCD-5s70%
“SLAM and a more natural ‘heavier’ presentation seem to be the future, with the MM-520 a welcome representative at this price point.”
Headfonics (Marcus)
hard to justify — a lot of money for this tuning, and no upgrade case for MM-500 owners30%
“Though at this price point that's far from an ideal FR.”
u/dagot23, r/headphones
