Solid Bass In-Ear Headphones with Lin-Line Mic and Controls Red. With newly designed drivers and in-line mic and control, the ATH-CKS990iS Solid Bass in-ear headphones give you portable, smartphone-compatible headphones with refined bass reproduction. The powerful 13 mm Dual Magnetic-Field Drivers feature an extra magnet in front of the driver to create a concentrated magnetic field that helps produce full, textured bass without distortion. Audio-Technicaâs specially designed Multiple-Transition Diaphragms with a diamond-like carbon coating add to the power and precision of the bass, as does the new Dual Bass Venting System, which utilizes two optimally placed vents in each housing for excellent air damping. The housings themselves are constructed of machined aluminum to reduce unwanted resonance and extend mid-to-high frequency response.