Depends … if it’s kit she uses frequently … or at least by the same OEM … then yes, she should, in theory, be able to find her way around it.

But, if not, then no, not really.

In fact, even two models by the same OEM can have significant differences; unlike every other mixer (including their own models), for the Xone:92, Allen&Heath decided that switching the channels in and out on the headphones required simultaneous pressing of buttons, not a simple toggle: whereas on every other mixer, listening to both channels simultaneously means simply pressing the button on the channel to be added, on the Xone:92, you have to turn the one you are listening to off then press both channels together — even if you’re well-versed in the use of A&H mixers, if you don’t know that about the Xone:92, the only way you’ll get it to work is by accidentally pressing both buttons as you mash them all in frustration … and, afterwards, you’ll be more inclined to think one of them is buggered than that it was the simultaneity that was the root of your success.

Also … how experienced is she? How often does she play? In the heat of the moment, our minds on other things, even the most experienced of us can be left floundering because we’ve forgotten (or overlooked) something — I once spent ages trying to figure out why my headphones suddenly weren’t working after they’d been perfectly fine five minutes before … (was it my headphones or was there a fault with the mixer?)… only to look down and learn that the problem was that, upon returning to the mixer from the gents, I’d forgotten to plug them back in again! If she doesn’t play out often then she could well be overlooking something obvious because, so far, she’s coincidentally never faced that issue and the thought, therefore, simply doesn’t cross her mind.