
AKG K702
Score: 77/100
Sennheiser HD 660S2
Score: 79/100Rankings

The Sennheiser HD 660S2 is an open-back, wired audiophile headphone delivering refined detail, deep bass extension, and a premium build. Its high impedance and lack of wireless or ANC limit use to desktop setups with a quality amp. Best suited for critical listeners and home-studio environments.

The AKG K702 is an open-back, over-ear reference headphone with a 45 mm driver and an expansive 10-39.8 kHz frequency response, delivering neutral and detailed soundstage. Its open design provides no isolation and the weight can be heavier than advertised, limiting use outside quiet studios. Ideal for critical listening and mixing in controlled environments.
| Attribute | ![]() | ![]() |
|---|---|---|
45 mmbest | 38 mm | |
| ↓ lower better | 235 gbest | 300 g |
62 Ω | 300 Ωbest | |
105 dB SPLbest | 104 dB SPL |
Click an attribute name to sort · Green = best, red = worst (relative to this comparison)
| Attribute | ![]() | ![]() |
|---|---|---|
Audio(4) | ||
Frequency Response | 10-39800 Hz | 8-41500 Hz |
Driver Size (mm) | 45 mm | 38 mm |
Impedance (Ω) | 62 Ω | 300 Ω |
Sensitivity (dB SPL) | 105 dB SPL | 104 dB SPL |
Build & Design(2) | ||
Weight (g) | 235 g | 300 g |
Dimensions (H×W×D) (mm) | 212x199x113 mm mm | 177.8x177.8x76.2 mm |


Products in the top-left offer the best value (high score, low price).

Professional reviewers commend the K702 for its comfort, neutral tonal balance and expansive soundstage, noting the flat-wire coil and Varimotion diaphragm provide linear performance. However, they criticize the lack of isolation, light clamping force and the fact that real-world weight exceeds the advertised spec, which can be a drawback for non-studio use.
Everyday users love the immersive, airy soundstage and the long-lasting comfort of the velour pads, often highlighting the detachable cable and replaceable pads as practical benefits. Common complaints revolve around the open-back leakage, heavier-than-advertised weight and the absence of isolation, making the headphones less suitable for noisy or shared environments.

Professional reviewers consider the HD 660S2 a significant technical upgrade over the original HD 660S, citing its refined voice coil, lower resonant frequency, and enhanced airflow as key contributors to superior bass extension, clarity, and overall resolution.
Everyday users praise the HD 660S2 for its detailed, balanced sound and comfortable velour pads, while noting the need for a solid amplifier and the open-back design's lack of isolation.
“Open-back leakage and zero isolation frustrate users in shared spaces”

“Actual weight often exceeds official 235 g spec (up to 300 g without cable)”


