Reason is a “programme with which you can become a professional musician emulating synthesisers, rhythm boxes, samplers, mix boards, effects, etc...”
With Reason “you can use as many instruments as you wish in isolation or along with another sequencer programme,” and you can do that in real time.
Reason is a programme which offers plenty of possibilities that can live up to all the musical expectations a professional may have. It is a fully complete program with all the options you expect. However, it is notworthy that this programme is not user-friendly: because of all its features it becomes more complex than usual, but the result is excellent.
Download Reason now and check it out yourself.