The AK380's First Accessory, AMP The primary goal of Astell&Kern has always been to deliver the original sound. We're proud to introduce the Ak380 Amp, an amplifier that supports high-impedance headphones and high-gain output while remaining faithful to the original sound. Expansion-type amplifier with design unity. 3,400 mAh large-capacity battery. 8.1 Vrms high-gain balanced output. 4.1 Vrms unbalanced output. Introducing Ak380 Amp, the first accessory to complement the Ak380. High Gain The Ak380 AMP supports 8.1 Vrms output when connected via high-gain balanced output. High-gain output is four times greater than low-gain output and supports high-impedance headphones. To protect earphones/headphones during high output, the volume is automatically adjusted when the amp is powered on or the earphones/headphones are disconnected. Furthermore, the gain can be easily adjusted via the AK380's settings. 3,400 mAh Large-capacity Battery An amplifier, which increases audio output, consumes a great amount of energy. Thus, the Ak380 AMP features a 3,400 mAh large-capacity battery – identical to the one in the Ak380 itself - to support up to nine hours of continuous unbalanced-output playback.