|You would be best off if you use a DAW (or a sequencer).
These are programs you can run on your pc or laptop that give you exactly that.
Would you want to run something like this on a hardware synth, be sure to save lots of cash. Do a search for synth workstations and you'll get what I mean.
A reasonably cheap and good sequencer that I also recommend is EnergyXT. It has a build-in synth even, and you can use VST instruments too. Since you can download VST instruments for free at KVR Audio, that would be your way to go I think.
You can ask me hundreds "why don't you" questions, answer will be, because it works that way too. - xTr1m