From the initial concept investigation, it might be assumed that I could plug the USB-midi device into my phone's USB-C port via an adapter and plug headphones into my phone's AUX port. The issues here is that AUX ports are being phased out of phones (including my current one) by many manufacturers. I was able to circumvent this by plugging a small USB-C dock into my phone, which houses ports for USB-C charging and 4 USB connections. I used one of these USB ports to plug in a USB to USB-C adapter, and then plugged a USB-C to 2.5mm aux adapter into the first adapter. Now I can take this setup anywhere, but I have to sprawl this rat's nest of adapters out wherever I go, find a spot to prop my phone up, and worry about snapping off a connector as I move the setup around or place it on any soft surface (connectors protrude from the sides of the hardware). Also, this setup uses my phone to power the controller, which drains battery quickly. While cumbersome, the tabletop setup is promising on a system level.