We compare products from their published specs and features; the verdicts below are our independent editorial opinions.
Updated: 2026-09-22 · 6 min read · Independent comparison
If you want a warm, non-fatiguing listen with genuinely deep sub-bass and a light 260 g frame, choose Sennheiser HD 660S2; if you need a reference-grade open-back for mixing and mastering with an ultra-wide 5 Hz–40 kHz range and a self-adjusting fit, choose Generic ATH-R70X.
• Sennheiser HD 660S2 — biggest strength: Vented magnet system and an airflow-optimised 42 mm transducer tuned to double sound pressure at the lowest octaves (27.5 Hz piano note, 45–60 Hz kick drum). That is real, physical low-end, not a bass boost.
• Sennheiser HD 660S2 — biggest trade-off: 300-ohm impedance and a 6.35 mm jack mean it wants a proper amp or desktop setup, and it ships with long cables meant for a desk, not a pocket.
• Generic ATH-R70X — biggest strength: Open-back aluminium honeycomb housings with a 470-ohm, 99 dB driver and a 5 Hz–40 kHz range — built for spatial accuracy and distortion control in critical listening.
• Generic ATH-R70X — biggest trade-off: That 470-ohm load is the highest in this comparison, so weak onboard audio will not drive it properly. It also runs a 3.5 mm jack with dual-sided locking cables — great for studio desks, less convenient for casual plug-and-play.
• Pick Sennheiser HD 660S2 if you want one headphone for long, relaxed music sessions with weight and warmth in the low end.
• Pick Generic ATH-R70X if you are mixing, mastering, or referencing and you want the flattest, most spacious picture of your track.
The HD 660S2 is a music-first headphone. Its whole design story is about getting more air moving: a 42 mm dynamic driver, an optimised surround, improved transducer ventilation, and a vented magnet system with steel mesh damping. The result, per the spec sheet, is minimal distortion and controlled air displacement — and a low end that reaches down to an 8 Hz rated floor with double the sound pressure at the lowest octaves. Practically, that means you feel the weight of a kick drum or the lowest notes of a piano instead of just hearing them.
The tuning is described as warm and relaxed with smooth treble, and the 300-ohm impedance with an ultra-light aluminium voice coil is there for impulse response and timbre. That combination is exactly what you want for a four-hour listening session where you are not chasing detail for a client — you are just enjoying the record. 104 dB sensitivity helps, but 300 ohms still means a decent amp gets the most out of it.
Buy it if you listen more than you analyse. Skip it if your source is a phone or a laptop headphone jack, if you need a 3.5 mm plug without an adapter, or if you want a neutral, surgical reference sound rather than something warm and forgiving. The open-back design also means it breathes — and leaks. That is the point of the design, not a flaw, but it belongs in a quiet room.
The ATH-R70X is aimed squarely at engineers and critical listeners. Its spec sheet reads like a studio tool: open-back aluminium honeycomb housings chosen for acoustic transparency, high-efficiency magnets and a pure alloy magnetic circuit to cut distortion, and a 5 Hz–40 kHz frequency response. The 470-ohm impedance and 99 dB sensitivity tell you this driver was built for voltage swing and control, not for easy driving.
The physical design is the other half of the story. At 7.41 oz it is a genuinely light headphone, and the 3D wing support system adjusts to your head shape automatically instead of relying on a rigid band you clamp down. Breathable fabric earpads round that out for long mixing or mastering sessions. Dual-sided detachable locking cables keep left and right signals independent, which matters when you are placing elements in a stereo field.
Buy it if your day involves a DAW, an audio interface, and hours of checking balances. Skip it if you want a plug-and-go headphone for commuting or casual listening — a 3.5 mm jack on a 470-ohm load will not be driven well by most consumer gear, and the open-back housings leak sound both ways. It also is not water resistant, which is worth knowing if you plan to move it around a lot.
• Best for deep, physical sub-bass → Sennheiser HD 660S2. It is explicitly engineered to double sound pressure at the lowest octaves.
• Best for mixing, mastering and critical reference → Generic ATH-R70X. Open-back aluminium honeycomb housings plus a 5 Hz–40 kHz range are built for spatial accuracy.
• Best for long, relaxed listening sessions → Sennheiser HD 660S2. Warm tuning, smooth treble, plush cushions, and only 260 g.
• Best for studio comfort during marathon sessions → Generic ATH-R70X. The 3D wing support self-adjusts to head shape and the fabric pads breathe.
• Easiest to drive from modest gear → Sennheiser HD 660S2. At 300 ohms and 104 dB it is the less demanding load of the two.
• Best for proper stereo separation on a studio desk → Generic ATH-R70X. Dual-sided detachable locking cables with independent L/R signals.
• Best for desktop convenience out of the box → Sennheiser HD 660S2. It ships with 4.4 mm and 6.3 mm cables plus a 6.3 mm-to-3.5 mm adapter and a protective case.
• Best for tight, leak-free environments → neither. Both are open-back by design and both let sound in and out. That is the trade-off you accept for the soundstage.
In my opinion, the Generic ATH-R70X is the one I would buy if my listening is work — mixing, mastering, referencing — because its 5 Hz–40 kHz range, transparent honeycomb housings, and self-adjusting wing support are aimed precisely at that job. But if your listening is pleasure, I would take the Sennheiser HD 660S2 without hesitation. Its vented magnet system, warm tuning, and 260 g open-back frame are built for sinking into music for hours. Match the headphone to the job and you will not be disappointed either way.
On paper, the Sennheiser HD 660S2. Its vented magnet system and optimised airflow are specifically designed to double sound pressure at the lowest octaves, with a rated range starting at 8 Hz. The ATH-R70X reaches lower on the number (5 Hz) but is tuned as a neutral reference, not a bass-forward listen.
The HD 660S2 is the friendlier load at 300 ohms and 104 dB sensitivity. The ATH-R70X sits at 470 ohms and 99 dB, so it needs more voltage to reach the same level. For both, a dedicated amp or a decent audio interface will get you closer to what the drivers can actually do.
Both are over-ear and both prioritise comfort. The HD 660S2 is 260 g with plush cushions and an open, breathable frame. The ATH-R70X is 7.41 oz with breathable fabric earpads and a 3D wing system that adjusts itself. It comes down to whether you prefer a soft clamp or an auto-fitting band.
For casual laptop listening, I would lean Sennheiser HD 660S2 — lower impedance, higher sensitivity, and an included adapter make it easier to live with day to day. If you produce music on that laptop, the ATH-R70X is the more purposeful tool, but budget for proper amplification. Either way, check the current price on Amazon before deciding.
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