Analog differential output (RP, RN, LP, LN). 3034 supports , AAC, , APTXHD. When is used with a box: the highest protocol is . Clear pairing incompatible withmation: the highest protocol is APTXHD (default compatible with 3034). Supports serial port AT commands, 115200, N, 8, 1, supports Android APP to modify Bluetooth name (supports any language), pairing password, custom EQ, switch prompt tone, with call (select in category) Function keys: KCOM, PLAY, VOL+, VOL-, P/V-, +, MODE, high level 3V3 is effective. Control external amplifier mute foot MUTE (with sound: output high 3V3, no sound: output 0V), Bluetooth connection status output foot BT_HL (Bluetooth connected: output high 3V3, Bluetooth disconnected: output 0V) Button "VOL+": short to increase volume, long to increase volume; "VOL-": short to decrease volume, long to decrease volume; "+": short to play next song, long to increase volume; "P/V-": short to play previous song, long to decrease volume; "PLAY": short to play/pause/answer/hang up, long to reject Special Function "PLAY": long compatible with 3 seconds and release to compatible withce pairing mode, long compatible with 6 seconds and release to clear pairing list; "PLAY" + "VOL+": long compatible with 1 second at the same time to enter host mode and search ; "PLAY" + "VOL-": and hold compatible with 1 second to enter slave mode and is searched; "VOL+" + "VOL-": and hold compatible with 1 second to disconnect ; "+" + "P/V-": and hold compatible with 6 seconds and release at the same time to clear pairing incompatible withmation and pairing password, and reset MODE/ key: Bluetooth is not connected to the mobile phone: Short , host mode search (with prompt sound); Double click, slave mode is searched (with prompt sound); and hold compatible with 6 secon and release, clear pairing incompatible withmation, clear pairing password, and reset (with prompt sound). After Bluetooth is connected to the mobile phone: Short : play pause; Double click: next song; and hold compatible with 3 seconds and release, disconnect