The Fiio E11K - Kilimanjaro2 - Portable Headphone Amplifier is designed for mobile Hi-Fi listening applications and is compatible with a wide range of headphones, earphones, and other in-ear-monitoring systems. The all aluminum-alloy body and chassis of the amplifier shields against electromagnetic interference and the built-in rechargeable 1400 mAH battery provides approximately 16 hours of operation on a four-hour charge via mini USB port. For I/O, it features an 1/8" stereo auxiliary input and an 1/8" stereo headphone output.
The device utilizes an OPA1642 as the voltage pre-amplifier and an AD8397 power amplifier to deliver a maximum power output of 450 mW at 16Ω (270 mW at 32 Ω) with a frequency response of 20 to 20,000 Hz, a signal-to-noise ratio of equal to or greater than 108 dB, and a T.H.D. of less than 0.004% into loads between 16 and 150Ω.
For controls, the amplifier includes a low-high gain toggle switch, a rotary volume control, and a fully discrete bass boost circuit that can be bypassed to decrease interference and lower the overall noise floor.