M50x Upgrade Guide: Best Headphones Beyond Audio-Technica

The Audio-Technica ATH-M50x is where a lot of people enter the hobby , including me. It’s a capable closed-back that earns its reputation as a starter headphone. But owner reports and measurement data consistently show that its mid-bass hump and compressed soundstage leave real performance on the table. The question isn’t whether to upgrade; it’s which direction makes sense for your listening habits.

This guide covers three headphones worth considering as your next step: the M50x itself as a reference point, the Sennheiser HD 600, and the HiFiMan Sundara. All three earn a place in the Buyer Guides section because the decision between them is genuinely non-obvious.

What to Look For in an M50x Upgrade

Tuning: Neutral vs. Colored

The M50x has a recognizable sound , elevated bass, a mid-bass hump, and a treble peak around 9 kHz. For many buyers, that tuning is fun and forgiving. But it also means you’re not hearing recordings as they were mixed. If your goal is critical listening , evaluating mixes, catching sibilance, identifying mastering decisions , a flatter response is more useful than an exciting one.

The two standard upgrade benchmarks are a neutral-warm tuning (HD 600’s territory) and a flat-extended planar response (Sundara’s territory). Neither is more correct in the abstract; the right answer depends on what you want to do with the headphone. Owner reviews on Head-Fi and ASR’s measurement database both support treating tuning preference as the first filter, not an afterthought.

Open-Back vs. Closed-Back

The M50x is closed-back. That matters for portability, shared spaces, and late-night listening without disturbing others. Both upgrade options covered here are open-back , which means sound leaks in both directions. Open-back headphones generally produce a more natural, spacious soundstage because the driver isn’t working against a sealed chamber. The trade-off is real isolation for none.

Before committing to an open-back, think honestly about where you listen. A dedicated listening space , a home office, a bedroom with the door closed , is the right environment for either the HD 600 or the Sundara. If you need a closed-back for commuting or shared offices, neither of these is the right upgrade, and exploring Buyer Guides for closed-back alternatives is worth the time before you spend.

Amplification Requirements

The M50x runs comfortably off a phone or laptop. Most open-back planar magnetics and many open-back dynamics do not. The HD 600 has an 300-ohm impedance and benefits from a proper amp, though the gap between a decent DAC/amp stack and a laptop headphone out is smaller than the forums sometimes suggest , real, but not transformative in the way planar amplification tends to be.

The Sundara is a planar magnetic. Underpowering it doesn’t just reduce volume; it affects dynamics and bass extension. Owner reports consistently flag that a mediocre source makes the Sundara sound thin. If you don’t already have a DAC/amp or aren’t willing to invest in one, the HD 600 is the more forgiving upgrade path. The Sundara rewards the stack investment clearly and measurably.

Build, Comfort, and Long-Term Ownership

The M50x’s clamping force is a known fatigue point for longer sessions. Both the HD 600 and the Sundara are lighter on the head and offer genuine all-day comfort by comparison. More importantly, both support long-term ownership: the HD 600’s cable and earpads are fully replaceable, and its driver has a service life measured in decades. The Sundara’s 2020 revision addressed the original’s earpad and headband comfort shortcomings specifically.

Build quality isn’t just about durability , it’s about whether a headphone stays in rotation five years from now or ends up replaced. The HD 600 has documented 10-plus year ownership histories across Head-Fi. For gear at this tier, repairability is a meaningful purchase criterion.

Top Picks

Audio-Technica ATH-M50x

Owning these since before the hobby took hold, the familiarity runs deep. They fold flat, they include three detachable cables in the box, and they’ve survived more hours of use than any other headphone in the collection. For a first closed-back, that utility still holds.

Where they fall short is on the measurement data that matters most for critical listening. The mid-bass hump , prominent around 200 Hz on ASR’s curve , adds warmth that reads as “bassy” rather than accurate. The 9 kHz treble peak creates a brightness that some listeners find fatiguing over long sessions. These aren’t catastrophic flaws; they’re the expected compromises of a consumer-friendly closed-back designed before the current generation of neutral reference standards. Verified buyers who use them as portable headphones rather than studio references tend to rate them highly. Buyers expecting flat studio-monitor performance are often disappointed by the branding.

The case for keeping the M50x alongside an upgrade is real , closed-back utility doesn’t disappear just because you own something better. But if the question is “what should I buy next,” the answer is almost never another M50x.

Check current price on Amazon.

Sennheiser HD 600

The Sennheiser HD 600 is the headphone the HD 600 has always been described as: a neutral-warm tuning with an outstanding midrange, an open-back soundstage that sounds natural rather than artificially wide, and a build designed for decades of ownership. Three years into owning these, the return rate is higher than any other headphone in the collection. Most sessions end here.

ASR’s measurement data shows a response that tracks closely to the Harman target in the midrange, with a gentle bass shelf that adds body without overwhelming the mix. The 300-ohm impedance means it needs amplification , but having run these off a Topping L50 at modest gain levels, the difference between that and a laptop headphone out is audible but not as dramatic as forum mythology suggests. A Schiit Magni Heresy or JDS Atom gets them performing at full potential without requiring a major investment. Verified buyers on Head-Fi and Amazon consistently note the midrange as the selling point , vocals, acoustic instruments, and strings in particular are rendered with a presence and texture that closed-backs at this tier don’t match.

The open-back design is a genuine constraint. Sound leaks in both directions, meaningfully. For anyone in a shared space or needing isolation, this isn’t the right answer. But for a dedicated listening setup, the HD 600 is the clearest step up from the M50x that exists at the mid-tier , not because it’s dramatically better at everything, but because it’s genuinely more accurate at the things that matter for long-term critical listening development.

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HiFiMan Sundara

Planar magnetic drivers do something dynamic drivers don’t, and the HiFiMan Sundara is where most buyers first hear it. The imaging precision , the ability to place instruments in a defined space rather than smearing them across a soundstage , is audibly different from the HD 600, not better in absolute terms but genuinely distinct in character. Detail retrieval at the top end is where the Sundara consistently draws owner praise: transients are faster, micro-detail in busy recordings is more exposed, and the bass extension is tight rather than elevated.

The 2020 revision , which is the version owned and referenced here , addressed the original’s most consistent criticism: earpad and headband comfort. The updated earpads are larger and softer. The headband distributes weight more evenly. For longer sessions, it’s a meaningful improvement. ZMF Universe earpads are also a well-documented aftermarket comfort upgrade that the community broadly recommends, which further extends the wear window.

HiFiMan’s quality control has been inconsistent enough that it warrants mention. Channel matching issues and driver failures have appeared in owner reports across multiple production runs. The 2020 revision improved this, but checking both channels on arrival is a practical step rather than paranoia. The amplification requirement is not optional , running the Sundara off an underpowered source compresses dynamics and flattens the bass in ways that undermine its core strengths. On a proper stack, the Sundara’s flat, well-extended response and planar imaging make a compelling case for being the better technical upgrade from the M50x, even if the HD 600 is the more immediately accessible one.

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Buying Guide

Choosing Based on What You Want to Hear

The most useful frame for this decision is not price tier but listening goal. The HD 600 is tuned for music enjoyment , its neutral-warm character makes long sessions natural and non-fatiguing, and its midrange rendering rewards vocal and acoustic material. The Sundara is tuned for detail and accuracy , its flat extension and planar speed make it more revealing of recording quality, both in good ways and bad ones. If your library skews toward pop, electronic, or heavily produced music, the HD 600’s more forgiving presentation is the better daily driver. If you listen to jazz, classical, or acoustic genres where imaging and micro-detail are directly musical, the Sundara’s planar character pays dividends.

The Stack Question

Neither the HD 600 nor the Sundara is the right answer if you’re not willing to add a DAC/amp. The HD 600 can function off a decent integrated amp or a modest stack; the gap between that and a laptop is real but not transformative. The Sundara does not perform well underpowered , this is documented extensively in owner reports and measurement follow-ups on ASR. Dedicated DAC/amp separates are worth the complexity specifically for planar magnetic headphones, and the Topping or JDS ecosystem provides solid entry-level options without significant outlay. If a stack isn’t currently in the budget, the HD 600 is the more practical upgrade choice until it is. Browsing the full headphone buying guides for stack recommendations before committing to the Sundara is a reasonable step.

Open-Back Is a Lifestyle Constraint

Open-back headphones are not simply “better” than closed-back , they’re suited to a specific use context. Both the HD 600 and Sundara require a private listening environment to function as intended. In a shared apartment, an open office, or a commute, open-back isolation is effectively zero, and sound leakage is significant enough to bother others nearby. A sealed alternative , the AKG K371 is the most commonly recommended neutral closed-back at this tier , is the more honest recommendation.

HiFiMan QC and Long-Term Ownership Risk

The HD 600 has a well-documented multi-decade service record. Replacement cables, earpads, and grilles are available directly from Sennheiser and through aftermarket suppliers. Owners on Head-Fi regularly report using the same pair for ten or more years with only earpad replacements. The Sundara’s ownership story is shorter and less consistent. HiFiMan’s QC variability is a real factor , not a reason to avoid the headphone, but a reason to purchase from a retailer with a clear return window, check both channels immediately on arrival, and consider it a slightly higher-risk purchase than the HD 600. The performance ceiling justifies the risk for buyers who are prepared for it.

Upgrade Path Thinking

The M50x upgrade decision has a longer arc than just the next headphone. The HD 600 tends to be a destination purchase , buyers who reach it often stop feeling the upgrade itch for years, because it sits at the intersection of excellent performance and genre versatility. The Sundara tends to be a waypoint , it reveals what planar magnetics do, which often leads to curiosity about higher-tier planars. Neither outcome is wrong, but they’re different trajectories. If the goal is to find a headphone and stop thinking about gear, the HD 600’s track record as a long-term reference strongly supports starting there.

Frequently Asked Questions

Should I upgrade from the M50x to the HD 600 or the Sundara first?

For most buyers, the Sennheiser HD 600 is the more practical first upgrade. It’s less demanding of amplification, more forgiving of source quality, and covers a wider range of genres without obvious weaknesses. The HiFiMan Sundara is the stronger technical choice for detail-focused listeners who already have or plan to buy a proper DAC/amp stack , but it rewards the infrastructure investment more than the HD 600 does.

Do I need a DAC/amp to use the HD 600 or Sundara?

The HD 600 benefits from amplification but can function adequately off a decent integrated source. The Sundara genuinely requires a proper amp , underpowered, its dynamics compress and its bass extension suffers in ways that owner reports and ASR follow-up measurements both confirm. For the Sundara specifically, a dedicated stack is not optional if you want to hear what the headphone actually does.

Is the M50x worth keeping after upgrading?

Owning the M50x alongside an open-back upgrade makes practical sense. The M50x provides isolation the HD 600 and Sundara don’t offer , for commuting, shared spaces, or late-night listening where open-back leakage is a problem. Treating it as a dedicated portable or secondary headphone rather than retiring it entirely is the approach that most owner reports and community discussions support.

How does the Sundara’s planar sound differ from the HD 600’s dynamic driver?

The most audible difference is imaging precision and transient speed. The Sundara places instruments in a tighter, more defined space and renders fast transients , percussion attacks, guitar plucks , with less smear. The HD 600 has a more natural, organic presentation that many listeners find more musical. Neither is strictly superior; they represent different approaches to accuracy, and listener preference between them is genuinely split in community discussions.

Does the HD 600 really need an amplifier, or is that forum exaggeration?

It needs one, but the gap is smaller than forum discussions often suggest. Running the HD 600 off a laptop headphone output is audibly inferior to running it off a proper stack , the dynamics are slightly compressed and the bass is less controlled , but it’s listenable. The improvement from a Schiit Magni or JDS Atom is real and worth the investment. The “requires a dedicated high-power amp” framing is an overstatement; the “benefits meaningfully from any decent amp” framing is accurate.