Sennheiser HD 660S2 vs Sivga Phoenix

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.

Sivga Phoenix

The Sivga Phoenix is a 50mm dynamic open back with CNC-machined zebrawood cups, stainless steel grilles and a listed 296g weight, and the physical product is the least contested part of it: premium materials with no visible flaws, a light clamping force, and a rated 32 ohm, 103 dB load that a phone or dongle drives without help. Tuning is where opinion divides. Listening-based reviews hear a warm, full-bodied signature: textured bass with sub-bass reach unusual for an open design, a lush and expressive midrange, and a treble that sits on the safe side of bright without fatigue. A measurement-based review reached the opposite conclusion, finding the response close to target only between roughly 100 and 500 Hz, with the emphasis concentrated at 200-300 Hz and a shortfall above, which it heard as dull and would not recommend in stock form. That same review reported a dramatic gain in tonal balance and spatial imaging once parametric EQ was applied. Soundstage width is also contested, called fairly modest and narrower than rival open backs in some listening and notably more expansive than a Sennheiser HD 600 in other listening. So are the stock pads, thin enough that one listener felt ears pressing against the driver covers after about an hour, while others logged multi-hour sessions without fatigue. Detail retrieval is a stated limitation: respectable, but described as neither the cleanest nor the most detailed at the price, with micro details sometimes going unnoticed.