After using the JVC HA-S160 for over a year and loving it, I decided to try this new compact JVC headphone. The HA-S140 is open with foam earpads, while the HA-S160 is closed with pleather pads. While the HA-S160 is closed, it doesn't isolate that well due to its small size.
The sound of the HA-S140 is okay, but not quite as good as that of the HA-S160. The HA-S140 feels very lightweight and flimsily built(lacking a metal band in the headband which the HA-S160 has), while the HA-S160 feels very ruggedly built. These are so close in price that it makes sense to buy the HA-S160 and avoid the HA-S140. The metal band in the headband of the HA-S160 makes such a difference in terms of fit and comfort. I hope JVC comes out with a new open headphone with a metal band in the headband and build quality similar to the HA-S160.