hi, tried the AP80 as a dac on my MacBook Pro. Works flawless. And also as a transport for the Mojo. The Mojo was connected with the supplied short OTG cable to the AP80 in USB "Audio" mode. Everything works fine there too. To my surprise the volume control of the AP80 has no effect. The volume is only controlled by the Mojo (as it should be). To answer your question, I hoped the digital-out would be fixed because I hoped the digital stream would bypass the dac section. (I suppose the gain should either be applied in or after the dac section. Not knowing the AP80s layout).