iBasso D18 Crotalus

The D18 Crotalus is a portable DAC and headphone amplifier with iBasso's R2R Ultra DAC, for use on the go or on a desk. The DAC combines a 20-bit R2R resistor network with a 4-bit string DAC in a fully differential eight-channel layout of 344 metal-film resistors, 76 of them in a compensation network; an FPGA and two Accusilicon femtosecond clocks handle the timing, with a NOS mode and four digital filters. Two TI dual op-amps and four BUF634A buffers deliver up to 1530 mW per channel from the 4.4 mm balanced output on battery, and up to 1750 mW with an external 12 V supply, with three gain levels. Besides USB-C (PCM 768 kHz/32-bit, DSD512) it takes coaxial and optical inputs, for example from a CD transport, and both outputs can also be used as line outputs. A 1.3-inch OLED screen and a rotary knob control it, the 3.5 mm output takes a headset microphone, and the 8.4 V battery lasts about nine hours. It weighs 271 g and comes with a leather case and a power adapter.

• iBasso R2R Ultra DAC, 344 resistors
• Up to 1750 mW per channel (4.4 mm, 12 V DC)
• USB-C, coaxial and optical in; about 9 h battery