To playback stereo recordings off a USB stick, playback defaults to ST3. Selecting the input source for ST3 to QU Drive allows processing on that channel. Is it possible to change USB playback to ST1. I tried changing the input source on ST1 but it will only indicate a blue X when I select USB, and ST3 is still displayed on the stereo playback screen.
A client wished to reserve ST3 playback for ipods etc and use ST1 or ST2 for USB stereo playback.
Thanks. BJ
I’m pretty sure stereo playback from qu-drive is hardwired to ST3.
Not the way I read the manual.
We play through a CD player and a PC into mono channels on the back of the board.
I think you can link mono channels with some of the other features on the board. Maybe mix or matrix does that.
We are a mono only set up so we convert stereo inputs from CD to two monos essentially; using a Y cable to split the signal into two inputs.
You could also play from a PC into the other stereo input using USBB input.
Plug the memory stick into the PC and play it from there into ST2.
A few corrections 
“Not the way I read the manual.”
QDrive stereo playback is always on ST3
“I think you can link mono channels with some of the other features on the board. Maybe mix or matrix does that.”
It’s the "Link function on the preamp screen. Any odd-even pair can be linked.
“We are a mono only set up so we convert stereo inputs from CD to two monos essentially; using a Y cable to split the signal into two inputs.”
Difficult to be sure what you mean here, but Y cables for combining are not recommended. More on that here: Why Not Wye
BJ.
How about just getting a Stereo minijack > 2 mono jack cable, so that iPods, phones etc can use ST1 or ST2?