The Ath-Dsr9Bt over-ear wireless headphones employs Audio-Technica’s new Pure Digital Drive system, which allows the headphones to operate without a sound-degrading D/A converter that conventional wireless headphones rely upon. Instead, the Ath-Dsr9Bt utilizes Trigence Semiconductor’s Dnote chipset to receive the digital audio signal from a Bluetooth wireless transmission, process and transfer it to the driver where the digital pulses of the chipset move the voice coil and diaphragm forward and backward to create the sound waves heard by the listener. The Pure Digital Drive system likewise depends on a re-engineered 45 mm True Motion Driver, which features a lightweight diaphragm with DLC (diamond-like carbon) coating for superlative fidelity and extended 5 Hz – 45,000 Hz frequency response. The driver’s 4-core twisted Ofc-7N voice coil provides precise control of the diaphragm displacement, and an acoustic resistor controls the airflow in front of and behind the diaphragm to ensure smooth, natural audio reproduction across the entire frequency range. The entire driver assembly is housed within a layered aluminum structure that minimizes unwanted resonance and isolates the electric circuitry from the housing’s acoustic space, resulting in optimal phase and transient response. The Pure Digital Drive system also enables the Ath-Dsr9Bt to overcome the sonic limitations of conventional Bluetooth wireless transmissions by supporting the 24-bit/48kHz Qualcomm® aptX™ HD codec. (aptX, AAC and SBC codecs are also supported.) The headphones can reproduce Hi-Res Audio when connected to a computer or other digital playback device via the included 2.0 m (6.6') USB cable. The Ath-Dsr9Bt is equipped with a microphone, volume control and simple tap control for answering/ending calls and playing/pausing music on a smartphone or other device. Three LED indicators allow you to easily monitor pairing and charging status, battery level, and the codec currently in use. The headphones’ internal lithium polymer battery provides approximately 15 hours of continuous use (up to 1000 hours in standby mode) and can be recharged using the included USB cable.