Sennheiser HD660S is housed in a foam-lined box according to the high-end product standards of Sennheiser hiend headphones. The box size is quite superficial and luxurious with black velvet color.
Accessories that come with the headset include 1 detachable cable with 6.5 mm 5-pin jack, 1 detachable cable with 4.4mm balanced jack and 1 3.5mm-to-6.35mm adapter.
Sennheiser HD660S has a simple design, quite crude but luxurious looking quite similar to the HD600/500 series. The mesh on the back is painted on the case where you can see the huge driver structure inside. Even the headband has been reworked more carefully to prevent scratches on the housing, so the headset is very durable.
With a large driver size, the earcup is quite large with an elliptical shape that covers the earlobes with just enough pressure. The earpad of the headset is produced quite thickly, increasing the soundproofing level worn in the hot summer, it is hot to know, and it is recommended that everyone use it in an air-conditioned room.
The sound quality of the HD 660 S series depends entirely on the mapping to produce a different sound quality. With this line of headphones, you can’t just plug in an Iphone or a laptop, a normal music player to listen.
With the precision and separation of the Chord line, the HD660s’ bass is much in volume and still has a roundness. Mid is warm and accurate, listening honestly feels like listening to a live singer.
Treble becomes quite smooth, bright sound, more flexible. When listening to music with brass instruments such as trumpet or saxophone, the sound is very sharp and smooth, while with the treble range of the violin line, the sound is quite smooth and smooth, and it sounds deep and emotional.