They are closely matched: Audio-Technica ATH-M40x scores 26/100 and Sennheiser HD 660S2 scores 24/100 in our overall comparison — within 2 points. Neither is a clear winner overall, so the decision comes down to the specific features and price that matter most to you.
Audio-Technica ATH-M40x vs Sennheiser HD 660S2
Updated Jun 2026 · Scored by the Let’s Compare Data Engine · How we score
For most buyers the Audio-Technica ATH-M40x is the better pick — it scores 27/100 to the Sennheiser HD 660S2's 24, leading on Comfort & Build. Choose the Sennheiser HD 660S2 instead if you want to spend less.
- Sound quality isn't scored yet (we have no measured audio data), so the score covers features, battery, noise cancelling and build.
Verdict
Our overall take, at a glance
Key takeaways
- Audio-Technica ATH-M40x and Sennheiser HD 660S2 are closely matched overall (within 3 points).
- Audio-Technica ATH-M40x stands out on Comfort & Build Weight: 240 g (8% less).
Audio-Technica ATH-M40x and Sennheiser HD 660S2 are closely matched
Audio-Technica ATH-M40x
27
Sennheiser HD 660S2
24
Where Audio-Technica ATH-M40x stands out
- Comfort & Build Weight: 240 g (8% less)
Watch-outs
Compromises to know before you buy
Audio-Technica ATH-M40x
- No microphone — you can't take calls.
Sennheiser HD 660S2
- No microphone — you can't take calls.
In-depth analysisAI
AI-generated from the cited sources — may be incomplete or inaccurate; verify important details before deciding · generated Jun 2026.
Audio-Technica ATH-M40x
The Audio-Technica ATH-M40x is an over-ear, dynamic closed-back headphone designed primarily for studio monitoring and audio production. Introduced as part of a remastered M-Series lineup in 2014, it features 40mm drivers with neodymium magnets and copper-clad aluminum voice coils. Operating with a 35-ohm impedance and a frequency response of 15 to 24,000 Hz, it is tuned to provide a flatter, more accurate sound profile with minimal coloration.
Best for audio mixing and studio monitoring requiring accurate, uncolored frequency…Best for content creation and tracking where a lightweight, closed-back design is…
Pros
- Equipped with two different detachable cables (a 1.2-meter straight and a 3-meter coiled cable) for physical flexibility
- Tuned for a relatively flat frequency response, helping to deliver accurate and uncolored audio reproduction
- Weighs 240 grams, presenting a relatively lightweight option for long listening sessions
- Includes a screw-on 6.5mm adapter to ensure compatibility with professional audio equipment
Cons
- Includes only a basic soft pouch for storage, offering limited physical protection compared to a hardshell case
Sennheiser HD 660S2
The Sennheiser HD 660S2 is a reference headphone model known for its clear, detailed, and warm sound signature. The design includes rich black velour earpads, and the headphones are noted for being lightweight. It provides impressive vocal clarity in the midrange.
Best for vocal trackingBest for classical musicBest for rock
Pros
- Features a fuller and warmer bass response than the original HD 660S
- The sound is described as clear, crisp, and detailed without sounding overly analytical
- Provides excellent detail and separation, with vocals prominently featured
- Is noted for being comfortable for long listening sessions due to light weight and earpads
Cons
- Can have a rather tight clamping force out of the box
- May not be suitable for genres requiring extremely thunderous bass (e.g., EDM or rap)
Value for Money
Which is the better deal for the price
Pre-filled with launch prices where known — enter today's price for an up-to-date check. Use the same currency for both.
Audio-Technica ATH-M40x
Sennheiser HD 660S2
Physical Comparison
Weigh them up, then compare real dimensions in 3D
Audio-Technica ATH-M40xSennheiser HD 660S2
Sennheiser HD 660S2 is 20 g (8%) heavier than Audio-Technica ATH-M40x.
Review Videos
Hand-picked expert reviews for each product
Detailed Specifications
The full spec sheet, side by side
Frequently Asked Questions
Common questions about Audio-Technica ATH-M40x vs Sennheiser HD 660S2 comparison
Audio-Technica ATH-M40x and Sennheiser HD 660S2 are compared side by side above across every spec in the headphones category — including performance, features and design — each scored 0–100 so you can see exactly where one leads the other. Our overall scores are 26/100 for Audio-Technica ATH-M40x and 24/100 for Sennheiser HD 660S2.
At launch, Audio-Technica ATH-M40x was the more affordable option ($99) versus Sennheiser HD 660S2 ($599). Weigh that against the overall scores (26/100 vs 24/100) and the value-for-money meter above to judge whether the higher-rated model justifies its price for your needs. Current retail prices vary — check the retailer.
It's close — Audio-Technica ATH-M40x (26/100) and Sennheiser HD 660S2 (24/100) score almost the same. Pick based on price and the individual specs that matter most to you; the comparison above shows where each one pulls ahead.
Which would you buy?
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