deepverified comparison
Sennheiser HD 660S2 vs HiFiMan Sundara — open-back audiophile headphones under 400 CHF
The verdict
Our pick → Sundara
The Sundara delivers planar speed and detail for roughly half the price — the smarter buy for most; the 660S2 rewards those with a good amp who prefer a warmer, more forgiving sound.
ValueSundaraEase of drivingSundaraBuild & bundled cablesHD 660S2
- Roughly half the price of the 660S2 for a fuller, more resolving planar sound
- Only 32 Ω and easy to drive — usable from a phone dongle or modest DAC/amp, whereas the 300 Ω 660S2 really needs a dedicated amp
- Wider treble extension and planar transient speed give it an edge in detail and imaging
Specifications
| Specification | HD 660S2 | Sundara |
|---|---|---|
| Weight | 260 g | 342 g |
| Connector | 6.3 mm + 4.4 mm balanced incl. | Dual 3.5 mm, single-ended |
| Impedance | 300 Ω | 32 Ω |
| Driver type | Dynamic, open-back (38 mm) | Planar magnetic (NEO Supernano) |
| Price (CHF) | 398 | 199 |
| Sensitivity | 104 dB (1 kHz, 1 Vrms) | 94 dB |
| Amp friendliness | Needs a capable amp (300 Ω) | Easy to drive (32 Ω), scales with power |
| Frequency response | 8–41,500 Hz | 6–75,000 Hz |
✓ marks the stronger value where it is measurable. Below the ~80 Hz crossover and for everyday use, some differences matter less than they look.