Memory Foam and Leather Headband For a touch of luxury, the HE-R9's steel headband is coated in high-end memory foam and supple leather. The memory foam provides a comfortable fit, while the leather is breathable and hard-wearing. The headphones are strong and lightweight, with a great musicality that is uncommon at this price. Finally, the striking crimson earcups are large enough to give the unique drivers enough volume to produce that stunning bass. Cable Connection – Dual Compatibility Mode The socket can accommodate both dual-sided unbalanced 3.5mm cable and single-sided 3.5mm balanced cable (left socket). The HE-R9 comes with a Dual 3.5mm TRS cable included only. Hi-res Bluetooth Bluemini add-on You can convert the HE-R9 headphones to wireless operation with the provided R2R. This unit just plugs in unobtrusively to one of the input sockets. This quality unit is also made by HiFi Man and uses the proprietary Himalaya DAC. Most modern streaming codecs are built in, such as LDAC, Aptx-HD as well as AAC and SBC. One of the best chipsets is used with the Qualcomm QCC5124. This has a frequency response of 20 Hz – 20Khz. Battery life is 6-7 hours.