One slider would be useful for having the cursor and chord change slightly 'forward' of the music. Having it /on/ the music is not terribly useful, traditionally the cue is a notch forward so you can prepare... like, half a beat.

The second slider would allow the playing to take into account the network delay of (some) airplay devices. The one in my lounge has several seconds buffer and it makes irealpro cue rather useless :-)