The Audeze MM-500 is one of the more significant professional headphones of recent years. Developed with 18-time Grammy-winning mix engineer Manny Marroquin and built on the same platform as Audeze's flagship LCD-5, it brought genuine studio-monitor accuracy to a headphone that working engineers could actually use without a separate amplifier the size of a suitcase.

Critics loved it. Professionals trusted it. The problem was bass: as with virtually all open-back headphones, the low end had limits. Open the back of a headphone and you gain soundstage and midrange openness; you give up some of the low-frequency weight and control that a sealed design can deliver more easily.

The MM-520 is Audeze's answer to that problem, and it is a compelling update. The central question is not whether it sounds good; given the MM-500 foundation, that was never really in doubt.

The question is whether the new SLAM technology closes the bass gap that has been the only credible criticism of its predecessor, and whether the overall package justifies the price step up from an already excellent headphone.

If you have spent any time around Audeze's professional range, the MM-520 will feel immediately familiar.

The design language is consistent with the MM-500 and the wider MM-Series: a machined aluminium chassis with Audeze's characteristic horizontal-line earcup design bisected by a vertical element, finished in a dark, slightly greenish-grey tone that reads differently under different lighting conditions. It is an understated piece of industrial design that looks expensive without drawing attention to itself, which is exactly right for a piece of professional equipment.

The headband is metal with a leather suspension strap, identical in philosophy to the MM-500, and the two 4-pin mini-XLR cable connectors sit at the base of each cup. The most significant aesthetic change from the predecessor is the earpads, which on the MM-520 are thicker memory foam units attached magnetically rather than glued into position. That magnetic attachment is a practical upgrade over previous Audeze models where changing or cleaning pads was a minor ordeal. Here it takes a couple of seconds.

At 555g, the MM-520 is a substantial object in the hand. It is worth being direct about this: the MM-520 is 60g heavier than the MM-500, which itself was not a lightweight headphone. The weight is the trade-off you make for the machined aluminium and the robust build quality, and in practice it is more noticeable when you pick them up than when you wear them.

For us personally, it has not been an issue, and as you will see in the comfort section, the headband design does a good job of distributing that mass. That said, if you are particularly sensitive to headphone weight over long sessions, it is the one figure worth factoring into your decision before buying.

The MM-520 is built around Audeze's 90mm planar magnetic driver, the same size used across the MM-Series and the company's LCD-5 flagship. Here is the full specification sheet:

Comparing directly to the MM-500: the impedance remains 18 ohms, the driver size is unchanged at 90mm, and the same Fluxor, Uniforce, and Fazor technologies reside within both. The sensitivity has nudged up from 100dB to 102dB per mW, a small but useful improvement in driveability. The headline addition is SLAM, which the MM-500 does not have.

An arguable downgrade, and it is worth naming it plainly, is the weight: 555g against the MM-500's 495g. That 60g difference comes from the thicker earpads and the additional acoustic engineering inside the cups, but if long-session comfort is your primary concern it is the one figure that gives you pause.

The MM-520 was designed as a professional mixing headphone, and that context shapes everything about it. Manny Marroquin used four years of real studio feedback to develop it, working across sessions for artists including Rosalía, Pusha T, and Lizzo, and the result is a headphone that prioritises decision-making accuracy over enjoyment. That sounds like a dry proposition until you understand what it means in practice.

A professional mix engineer needs to know, with confidence, that what they are hearing on their headphones accurately reflects what a mix will sound like on speakers, in a car, on earbuds, and on a club sound system. If your monitoring reference flatters the low end, you pull the bass back too far. If the midrange is coloured, vocals sit wrong.

The MM-520 aims to eliminate those variables by giving you the most accurate possible picture of what is actually in your mix. Working engineers describe this as translation: the ability to make decisions that translate reliably to other playback systems.

But the MM-520's use case extends well beyond the studio. The same properties that make it an exceptional mixing tool, an accurate, low-distortion presentation across a wide frequency range with strong imaging and minimal colouration, also make it a strong music listening headphone for anyone who wants to hear recordings as they were mastered.

For a serious music listener, putting on the MM-520 for the first time and hearing familiar recordings reveal details that other headphones either colour or smooth over is an eye-opening experience. These are headphones that reward careful listening, and the electronic music audience in particular stands to gain from what they offer: the decay of a reverb tail, the precise placement of elements in a stereo field, the texture of a synthesised bass note.

Worth noting: the open-back design means sound bleeds both in and out. These are not headphones for public transport, shared offices, or tracking vocals near a microphone. They are for quiet environments where you want to do your most serious listening.

For a headphone that weighs 555g, the MM-520 is comfortable to wear. The leather suspension strap on the headband distributes the weight across the top of the skull rather than concentrating it at a single point, which makes a significant difference in how the mass is perceived over time.

The upgraded memory foam earpads are thicker and more plush than those on the MM-500, and they seal around the ear with enough softness that the clamping force, which is moderate rather than tight, does not translate into any meaningful pressure on the ear. Extended sessions of three or four hours pass without the kind of fatigue that the weight on paper might suggest, which for a headphone this substantial is no small thing.

The magnetic earpad attachment is worth singling out again here: the ability to detach and reattach the pads cleanly and quickly also makes cleaning them far more practical, which matters for any piece of equipment that sees daily professional use.

The SLAM technology, standing for Symmetric Linear Acoustic Modulator, works by managing air pressure inside the earcup to extend and control low-frequency reproduction. On an open-back headphone, where the rear of the driver is exposed to the open air, maintaining bass pressure is an inherent engineering challenge. SLAM is Audeze's solution, and in the MM-520 it delivers a clear and audible improvement over the MM-500 in the low end.

The bass is not emphasised or boosted in the way a consumer-oriented headphone might handle it. Instead, it is controlled, extended, and honest. The sub-bass reaches further than most open-backs at this price, with a naturalistic texture that makes bass instruments feel present rather than implied.

The mid-bass is tight and fast, with transient response that a planar driver handles with considerably more precision than a conventional dynamic driver of the same size could manage. For electronic music in particular, where the relationship between kick drum and sub-bass is a fundamental mixing decision, the improvement in low-frequency clarity that SLAM delivers is worth noting.

The midrange remains the heart of the MM-520, as it was with the MM-500. Voices and instruments occupy precisely defined positions in the stereo field, with a neutrality that makes the headphone feel transparent rather than characterful.

The imaging has a quality that is more reminiscent of a well-set-up pair of near-field monitors than a typical headphone presentation: it is not trying to impress you with a wide, theatrical soundstage, but giving you an accurate and organised picture of where everything sits in the mix.

The top end has a slightly airier quality than the MM-500, with reverb tails and high-frequency details presenting a little more spaciously. Cymbals have a clean, realistic crack rather than the brittleness that cheap drivers introduce.

One area where the MM-520 makes a clear improvement on its predecessor is the upper midrange. The MM-500 could tip into a slight forwardness in that region on certain recordings, a brightness that occasionally drew attention to itself rather than disappearing into the music.

The MM-520 corrects this with a more even balance between the upper mids and lower treble, and the result is a presentation that sits comfortably through longer sessions without forcing you to reach for the volume dial.

If you own and love an MM-500 it is worth hearing the MM-520 before assuming it is an automatic upgrade; the character has genuinely shifted, and whether that suits your taste is a personal call.

Yes, with one important caveat: £1,699 is not a starting price, and it should not be. The MM-520 is a professional instrument designed for people who mix music for a living or who are serious enough about listening to music that they want reference quality at home.

If you are a mixing or mastering engineer looking for a headphone that will improve your decision-making confidence in sessions, particularly in the low end, the MM-520 delivers on that promise convincingly. If you are a serious listener for whom understanding exactly what is on a recording matters as much as enjoying it, these headphones will show you things that consumer-oriented alternatives paper over.

The MM-520 has earned a Waveform Wavemaker editorial award from us: it is a well-considered step forward from an already strong platform, and one of the more worthwhile professional headphone releases of 2026.

If the price gives you pause, the Audeze MM-100 is the place to start. It uses the same planar magnetic driver philosophy, the same commitment to neutral and accurate reproduction, and the same Manny Marroquin collaboration, at considerably less outlay.

The MM-100 does not have SLAM, the chassis is less premium, and the overall resolution is a tier below the MM-520, but for anyone who wants to understand what the Audeze sound is about before committing to the flagship, it is the obvious and sensible entry point.