AudioChainsDB
Superlux

HD669

headphones

$45

Used market: $35*

Manufacturer datasheet

Specifications

3 of 7 values have a recorded source
Connector
3.5 mm mini stereo, detachable single-sided·
Form Factor
Over-Ear·
Is Closed Back
yes·
Impedance ohms
56✓
Transducer Type
Dynamic·
Detachable Cable
yes·
Sensitivity dB mW
98✓

Expert Audio Engineering Commentary

Tonal Profile

The closed sibling of the HD668B: same 56-Ohm load, same detachable cable, sealed cups. Power handling drops to 200 mW against the HD668B's 300 mW, which is a limit on abuse rather than on listening — 200 mW into 56 Ohms is 3.3 V, far past any level you would keep on your head.

* Estimated with the depreciation fallback (~78% retained value). · checked on 8/5/2026