The first JVC HA-S660 review is up at http://earphone.it168.com/a2013/0823/1525/000001525231_all.shtml
Here is the gist:
Low dive is good, feeling of control is good, but a little lacking in the extension.
Human voice is clear and smooth, strong sense of line, very suitable for listening to pop music.
High-frequency part sounds transparent, a sense of space and field is good.
HA-S660 resolving power is also good, in the high-frequency side with outstanding performance, the sound is transparent, strong spatial sense, vocal and instrumental sound clear and legible. When worn can isolate well from external noise and is comfortable to wear, no pressure.
Earmuffs are made of a soft leather package.
The accessories are lacking
Don't know what is reviewer's reference here, no comparisons were made.
However, for a carbon diaphragm that wasn't burned in yet, sounds promising.
I imagine they sound similar to HA-S400 with HM5 pads
Edited by BenF - 10/22/13 at 6:50pm