https://en.cayin.cn/down1/show?id=13581 Announcement of Cayin N5ii Firmware v3.9en New Functions and System Optimization 1. Solved delay after user pressed the play/pause button during music playback. 2. Reset USB Audio Out to the default configuration (noise may occur when playing PCM and DSD files). *The main purpose for v3.9en firmware is to solve the delay after user pressed the play/pause button during music playback. However, if the user unplugs and plugs the earphone after started up the device, the delay (play/pause button and prev/next song buttons during playback) would remain. Due to hardware and system limitation, v3.9en firmware will reduce the performance and compatibility of USB Audio Output. We advise users to choose this update based on their needs.