I'll leave the presets part to others, but just a short remark about turning pre-emphasis off: If you do that, unless the transmitter contains some form of processing, you'll have to set the output level very low to transmit without creating too loud sounds.
Reason: In this case, the transmitter is performing pre-emphasis. Which greatly increases the level of highs, which in turn causes spikes in the total output level.
So, leave pre-emphasis on (but not pre-emphasize output!). This makes sure that Stereo Tool processes the audio based on pre-emphasis, but outputs a signal that is not pre-emphasized.
If this causes a too big drop in the high frequencies, try lowering the 'Loudness' slider a bit. That gives all the sounds (and the highs are very loud) more space.
If you want to listen in mono, turn Stereo Boost off, turn Stereo Image on, and set the 'phase' and 'width' sliders to 0 - this gives a mono sound that 'sounds like stereo' - sounds don't cancel out each other as they would normally do. The output is completely mono if you do this - if you want a bit of stereo to remain, only set the 'phase' slider lower, and keep 'width' where it is.