Small aluminum shell, simple dismantled back screw design, can easily remove the screw, open the machine can replace the battery. Two pcs 9V lithium batteries need to be used in RA1 Mousai RA1 used the JRC 4556AD Opt-Amplifier IC , both its voice performance and driving power are extremely excellent. The new version of the Mousai RA1 changed circuit design to make the voice more clean, and brighter ,it also changed the volume control knob to make itself become more human and feels good. In addition , new version increased the power anti-shock pad so that you can use the more confidence. Mousai RA1 driver Goethe, Alice, Iron Triangle and other low-impedance headphones outstanding performance!