I don't know much about samplers, but I have an full sized Behringer x32. There's a rack version with software control. There's an android app too. The things a beast. 40 channels. 16 mix busses. 32 inputs, 16 outputs, plus two house outs. 100 full board presets. It can store channel presets too. I have mine hooked to a midas pro stage box, for the quality preamps.

But if what you're looking for is a controller (faders etc that control a virtual mixer) and not an actual mixer, presonus make some quality gear, and I believe it can be used via standard midi. They also have the "faderport" which is like an all purpose single fader controller. And it looks like they have multifader versions now.

I use one of these as a controller, because the multifader faderport didn't exist when I needed a controller. It's a hefty piece of hardware. You can shift banks if the mixer / busses exceed the number of physical channels.