As Elf suggested, I loaded all audio clips to the laptop and used the free version of QLab which allows quite a level of sophistication (fades in/out, one clip triggering the next, different outputs per clip for spot effects), all from the jab of the space bar- with a bit of pre-show preparation.
QLab I think is mac only but Soundcue is a pc equivalent and I believe there are freeware alternatives.
The drama group asked me to rig a similar system in their home theatre and i recommended installing SoundCue or a freeware alternative on a redundant PC and buying this cheap and cheerful multi-out interface:
8-out USB interface
But as usual, once expenditure on their part was mentioned, their eyes glazed over and I was expected to do same with two sticks and a coke can the female lead found by the back door.