Focal Bathys vs Sennheiser HD 660S2

Focal Bathys

The Bathys is a closed-back wireless ANC over-ear built around a 40mm aluminium-magnesium M-shaped dome driver, and it is judged first on sound. The tuning follows a Harman-leaning philosophy: smooth and fairly dense, with a clean midrange called a standout in its class, vocals forward without shouting, and a top end that relaxes from about 4kHz so sparkle is limited while sibilance is effectively absent. Bass is where accounts split, between a lifted shelf peaking around 50Hz that reads as powerful and punchy, and a low end described as subdued, or as deep sub-bass rumble that reserves itself rather than dominating. Staging divides the same way, from among the best heard on a Bluetooth over-ear to a rounded, intimate space whose distance portrayal leaves something to be desired. Running the headphone over USB-DAC instead of Bluetooth tightens the low end, adds treble bite and enlarges the stage. Build draws less argument: magnesium yokes, an aluminium headband, leather and memory foam pads, 350g, and no creak in the articulation. Noise cancelling is strong below roughly 1-2kHz and lets more midrange and voice through, and it is placed behind the Sony, Bose and Apple flagships, with low-frequency attenuation measured close to 20dB. There is no LDAC and no passive mode, so a flat battery means silence. Price is the standing objection: it launched at $799, and one verdict is that less expensive alternatives cover most of the same ground.

Sennheiser HD 660S2

The HD 660S2 is a driver-level revision of the HD 660S rather than a new headphone. The voice coil was reworked and impedance moves to 300 ohms, matching the HD 600 and HD 650. The low end is the headline change: sub-bass extends further and the mid-bass carries more body than the predecessor, with the missing fundamental in lower-register instruments described as finally present. The tuning still stays measured rather than bass-forward, and it is explicitly not aimed at bass-heads. Tonally it sits between the HD 600 and HD 650 with a lean toward the HD 650, cleaner through the mids than the HD 650 and less forward than the HD 600. Treble is where reviewers split: one account hears considerably more bite, sizzle and crispness than the original without harshness, while another frames the profile as relaxed and deliberately not treble-emphasized. Staging is reported as taller and deeper with more precision than the predecessor, though the presentation is still called intimate rather than expansive. A dip through roughly 3-5 kHz is flagged for dimming detail on some tracks, with a few dB of parametric EQ offered as the remedy. The chassis, velour pads and headband carry over unchanged, and the packaging is judged a downgrade. Value is the real fault line: at a street price near $500 one verdict reads it as a clear technical step up on the HD 660S, while another concludes it does not differentiate itself from cheaper models in the same family and tells existing HD 660S and HD 600 owners to save their money.