Meze 105 AER vs Sennheiser HD 660S2

Meze 105 AER

Meze's lightest open-back at a rated 336 g, the 105 AER pairs ABS-PC earcups and a metal frame with a self-adjusting suspension headband and breathable velour pads, and it is built to come apart so worn parts can be replaced. Comfort and drivability are the traits reviewers keep returning to: rated at 42 ohms and 112 dB, it reaches loud, clean levels from a MacBook headphone jack or a small dongle, while dynamics, imaging and clarity firm up when it is given a better source. The tuning reads warm-leaning and forgiving, and the midrange is picked out as the high point: a clean bass-to-mid handoff climbing to a 3 kHz hump, natural timbre on acoustic instruments, and vocals that are intimate and full without shouting. Bass carries a light emphasis weighted toward midbass punch and holds structure rather than bloating, though how much sub-bass rumble is really there is disputed. Treble is the contested region: it is described as smooth and rolled off with a recessed 6 kHz that softens note attack and costs bite, and also as sparkly, crisp and a favorite quality. Staging divides the same way, called wide with good left-to-right spread on one hand and surprisingly narrow in stereo width on the other, while imaging and layering are treated as a strength either way. Against the 109 Pro at twice the money it is warmer, smoother and clearly behind on resolution, extension and sparkle. The single-ended stock cable is the recurring packaging complaint.

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.