GLD-80. Can I use a USB mic for the talkback channel? 16 July 2021 14:30 No, the talkback mic has to be routed from a GLD input, USB microphones are not compatible. Related articles GLD-80. USB playback, folders not visible GLD. What codecs are supported for USB audio playback? GLD. Editor GLD. Can I daisy chain two GLD-AR2412 using the Expander port? GLD. What is the maximum number of software applications that can be connected to a GLD simultaneously?