If you want to experiment, you can use panning for creative effects, such as giving a mono synth signal a stereo spread. This can be done by using equalization to divide the signal frequencies and then panning each division into its own space. Although ambience can be created in a mix by using digital reverbs and delay units, you can sometimes get a better effect by feeding the signal both direct and from a speaker. The speaker can be miked close up, which will produce delays and reverb times shorter than any reverb unit can provide, and also farther away. You can then mix the direct signal and the mic signals in whatever proportions you want.
Experimentation is the key.
When they are fed excessive signal levels, digital signal processors are particularly unforgiving and can create a dirtying effect during the mixdown.