I seem to remember somebody saying they’d plugged a tablet into the USB B port via a camera adaptor of some sort. Was quite a while back, and I can’t find the post now….
That was about multitrack streaming via USB: Qu and iOS streaming and Recording to iPad
So I guess streaming only stereo should work as well. I’m personally using AirPlay since I do have a wireless connection for remote control anyway.
AirPlay is a function of an Apple AirPort Express router, which I always have attached for wireless remote control my Qu. Just strap a Mini-TRS to 2xTRS cable into ST1 or ST2 inputs and switch playback on your iPad to use AirPlay.