DSD Full Balanced Portable Headphone Amplifier, manufactured by RATOC. - Brand: RATOC Systems, Inc. - Model Name: REX-KEB02iP Key Features: Equipped with two modes: USB-DAC mode and iPod compatible mode. Supports DSD64/DSD128, and L-PCM up to 24bit/384kHz. Full balanced circuit configuration to maximize expressive power. Equipped with a digital filter switch. Employs the renowned ESS DAC "ES9018K2M". Features two output systems: balanced and single-ended output. The balanced headphone drive circuit provides powerful drive through BTL connection. Employs a single-ended amplifier with a dedicated filter circuit for balanced input. The built-in power supply also uses a high-quality, domestically produced lithium-ion rechargeable battery. Product Specifications: Model Number: REX-KEB02iP Name: DSD Compatible Full Balanced Portable Headphone Amplifier Input Terminals: [USB] USB Standard A: For connecting iPod, iPhone, and iPad in iPod compatible mode. USB Mini-B: For connecting to a computer (Windows PC/Mac) or Lightning-USB Camera Adapter, SONY WMC NWH-10. USB Micro-B: For charging the built-in lithium-ion battery. Output Terminals: Headphone Output: Non-clip maximum output 2.5Φ mono: 1.7Vrms/131mW per channel (22Ω load) 3.5Φ stereo: 1.62Vrms/38.0mW per channel (68Ω load) Switches: Power switch (integrated with volume knob) Headphone level switch (Low ⇔ High) Input selection switch (iPod ⇔ USB-BT ⇔ USB-BP) Digital filter selection switch (Slow ⇔ Sharp) Compatible Headphones: Headphones or earphones with a 3.5Φ stereo mini-plug Balanced connection type headphones or earphones with 2.5Φ micro-mono plugs (mono x2) for left and right channels. Power Supply: Built-in rechargeable battery. Charging adapter input voltage range 4.75V〜6.6V (USB Micro-B) The box shows signs of tape removal and use. The main unit has no noticeable scratches. Please check the photos. The included accessories are shown in the photos. Operation has been confirmed.