My MX49 has two-way audio over USB (including MIDI out signal) connection. Connecting MX49 to for example iPhone sends MIDI signal to iPhone and sound from MX49 to iPhone and receives sound from the iPhone that can be heard in headphones or audio out connected to MX49. Local sound on MX49 can be disabled in order to hear only iPhone sounds generated using MIDI signal from MX49. Here is my question: When I connect MX49 only to iPhone via Apple USB Adapter and nothing else (except power of course) - no headphones or audio out connected to MX49. I open iPhone app that allows MIDI input. I can not hear sounds on the iPhone. The sounds generated by MIDI signal are sent back to MX49 and not played on the iPhone. Audio level on my iPhone is "locked" and showing connected to MX. I can see that MIDI signals are correctly sent from MX49 as virtual keys in the iPhone app are moving. The two-way audio through USB in MX49 somehow "hijacks" audio from iPhone and wants to play it back through its own audio out only. Why would I want to do it? Well, I could take with me only MX49 and iPhone so that iPhone would work as a speaker. It can can be done with "simple" MIDI controller. For example my Casio Privia PX-870 digital piano works just like that. I can play iPhone sounds through iPhone speakers and not have to use Privia speakers. The same "audio lock" behaviour is on my Mac. I wonder if there is a setting in MX49 that allows for it to send only MIDI signal and not influence the audio channels? Otherwise perhaps there is an app on iOS that allows to modify how the audio flows? Or the third option would be to connect MIDI out to USB?