Sennheiser HD 620S vs Sivga Phoenix

Sennheiser HD 620S

The HD 620S is a closed-back headphone built on a 42mm dynamic driver, listed at $349.95, rated 150 ohms and 110 dB/Vrms, and easy enough to drive that reviewers report full volume from a phone, an Apple dongle or a game controller. Three points are settled across the coverage: passive isolation is unusually strong for a sealed passive design, out-of-box clamping force is high and eases with wear, and the bass you actually hear depends heavily on seal. Everything else splits. One camp hears a near-neutral, HD 600 adjacent tuning with clean mids and a wide, natural stage for a closed back. The other measures and hears an asymmetric W-shaped response: strong sub-bass, a trough near 200 Hz, a 400-800 Hz hump that reads as boxy, a lower-treble recess and a mid-treble lift that leaves the highs sounding disconnected. A measurement-led review scored it 6.5 out of 10 with a 2.9 predicted-quality mean and called the price hard to justify, while a measurement forum still placed it on its recommended list. Detail and dynamics divide the same way.

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.