Brian, Probably the USBAudio driver is getting confused because of this: FTDscr: db FTDscrEnd-FTDscr ;; Descriptor length db CS_INTERFACE ;; Descriptor type db FEATURE_UNIT ;; Descriptor sub-type db 2 ;; Identificador del Feature Unit db 1 ;; ID de la Fuente de se=F1al db 1 ;; Control Size db 03H ;; Controles Master ch: Mute y Volumen db 00H ;; Controles ch 1: Ninguno db 0 ;; Nombre de la Feature FTDscrEnd: Where you have placed the volume control on the Master channel and not on ch.1. Thanks. Devendra. ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.de/