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If you want a lightweight, high-sensitivity wired monitor you can drive straight from a laptop or phone for Zoom calls, choose Superlux HD661; if you need a rugged, flat-response studio headphone with swiveling ear cups and a detachable cable, choose Audio-Technica ATH-M40x. Both are wired, closed-back designs, so neither is a Bluetooth or spatial-audio solution — if you were hunting for the best Bluetooth earbuds for Zoom calls, this is not that article. What follows is a spec-based comparison for people who actually care about how each pair behaves on a long call.
• Superlux HD661's biggest strength: 102 dB sensitivity at 68Ω means it gets loud from modest sources, and you get two cables (3.3 ft and 9.8 ft) plus a pouch and a gold-plated 3.5 mm-to-6.3 mm adapter in the box.
• Superlux HD661's biggest trade-off: Plastic enclosure, 6.72 oz, no swiveling cups and no detachable cable — the cable is fixed, so a snag on a desk chair is a permanent problem.
• Audio-Technica ATH-M40x's biggest strength: Flat-tuned 40mm drivers with copper-clad aluminum voice coils, aluminum enclosure material, 90-degree swiveling ear cups and a detachable single-sided cable system.
• Audio-Technica ATH-M40x's biggest trade-off: It's the heavier of the two at 8.5 oz, and it's built around studio tracking and mixing rather than casual listening.
• Who the HD661 is for: Anyone who wants an inexpensive-feeling-in-hand but sensitive closed-back monitor for calls, tracking on a budget, or broadcast work in noisy rooms.
• Who the M40x is for: Someone who needs one reliable pair for studio tracking, mixing and DJ monitoring, and who values swivel cups and replaceable cables.
The HD661 is an enclosed (closed-back) headphone built around a 40mm dynamic driver with a neodymium magnet. Its headline spec for call use is sensitivity: 102 dB SPL at 1 mW at 1 kHz, paired with 68Ω impedance. In plain terms, that combination is friendly to weaker outputs. A laptop headphone jack, a cheap USB audio interface, a phone with a dongle — none of those need to strain to get the HD661 to a usable level. For Zoom calls specifically, that matters more than people admit. You want to hear your own voice at a comfortable volume without cranking a software gain slider into hiss territory.
Who should buy it: someone who wants a sensitive, isolating closed-back headphone for voice work, live monitoring on a tight budget, or broadcast-style use in a loud room. Someone who moves between a phone and a desktop and doesn't want to think about amplification.
Who should skip it: anyone who wants a detachable cable, swiveling cups or a metal build. The enclosure is plastic, the cable is fixed, and at 6.72 oz it's light but not built for being thrown in a bag nightly. If you need one pair to survive years of studio abuse, keep reading.
Audio-Technica ATH-M40x: Who It's For
The ATH-M40x is a 40mm neodymium-driver monitor headphone with copper-clad aluminum voice coils tuned for flat response. Flat here is the whole point: it's designed for studio tracking and mixing as well as DJ monitoring, which means it isn't trying to flatter your music. If you're on a Zoom call, flat response translates to voices sounding natural and un-hyped rather than bass-boosted. That's usually what you want when you're listening to other people talk for an hour.
The feature that separates it most clearly from the HD661 is the 90-degree swiveling ear cups. That enables single-ear monitoring — flip one cup up and off your ear, keep the other on, and you can hear the room while still hearing your feed. If you do any kind of live work, podcasting with a co-host in the room, or you just want to hear a knock at the door mid-call without yanking the whole headset off, this is a real quality-of-life difference. The circumaural, around-the-ear fit with sound isolation is the same basic idea as the HD661, but the enclosure material is aluminum instead of plastic, and it weighs 8.5 oz.
Who should buy it: someone building a small studio or home recording desk who needs one dependable pair for tracking, mixing and monitoring, and who wants swivel cups and a replaceable cable.
Who should skip it: someone who wants the lightest possible thing on their head for a two-hour call marathon, or who wants to plug straight into a weak phone output and expects lots of headroom. The M40x is a studio tool, not a featherweight commuter headset.
Side-by-Side: Which Should You Choose?
• Best for plugging straight into a laptop or phone → Superlux HD661. Its 102 dB sensitivity and 68Ω impedance make it the easier load to drive.
• Best for flat, uncolored voice reproduction → Audio-Technica ATH-M40x. It's explicitly tuned for flat response.
• Best for single-ear monitoring → Audio-Technica ATH-M40x. The 90-degree swiveling cups exist for exactly this.
• Best for cable longevity → Audio-Technica ATH-M40x. Detachable single-sided cable system beats a fixed cable.
• Best for long-call comfort → Superlux HD661. At 6.72 oz versus 8.5 oz, it's the lighter pair on your head.
• Best for build materials → Audio-Technica ATH-M40x. Aluminum enclosure versus plastic.
• Best for cable length flexibility out of the box → Superlux HD661. A 3.3 ft and a 9.8 ft cable are both included, plus a clip and adapter.
• Best for a mic-stand-based desk setup → Audio-Technica ATH-M40x. The bundled holder and folding design suit a fixed studio position.
If I were buying one pair for Zoom calls and light studio work, I'd take the Audio-Technica ATH-M40x. Flat tuning, swiveling cups for single-ear monitoring, an aluminum enclosure and a detachable cable are the four things I'd personally pay for, and they all point the same direction. The HD661 wins on weight and on how easily it's driven, and for a pure call-and-listen setup that's genuinely enough. But for a headphone I'd expect to keep and maintain, the M40x is the one I'd recommend to most people.
Both work, since both are wired closed-back headphones with sound isolation. The HD661 is lighter and easier to drive from a laptop jack; the M40x sounds flatter and lets you flip one cup off your ear. For pure call comfort I'd lean HD661, for natural voice tone M40x.
Yes. It uses a detachable single-sided cable system, and both a coiled and a straight cable are included. The HD661's cable is fixed, so if cable damage is your main worry, that's a decisive difference.
The Superlux HD661 is 6.72 oz; the Audio-Technica ATH-M40x is 8.5 oz. Neither is heavy, but if you wear headphones for hours, that roughly 1.8 oz gap is noticeable.
They're both adult-sized over-ear designs rather than child-specific headsets, so I wouldn't call either a kids product. Also note both are wired — neither is a Bluetooth or spatial-audio headphone, so if that's what you're after, look elsewhere.
I don't publish prices here because they change constantly. Check the current price on Amazon using the button on this page and compare the two side by side before deciding.
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