I would certainly try connecting the output from the laptop's stereo mini-jack to one of the pre-amp rca inputs as a starting point.

The mixer you showed should be OK, but maybe is not required.

And yes, you can choose MIDI only styles, although the RealTracks are worthy of consideration IMHO. To choose MIDI only, in the StylePicker press Clear first, then select MIDI only from the Type drop-down.

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