new project/architecture questions

hello,
I begin a project of sound machine.
I'd need to target the optimal micro-controller for this.
I'd probably build my PCB.

The project requires few buttons, few leds, 1 LCD and severa potentiometers. I/O aren't the main constraint ; I can use mux/demux too.

The main constraint is I want to use 2 sound creation mode:

  • based on digital synthesis (algorithms making sounds rock !)
  • based on audio samples stored inside a memory (?) and which could be replaced through an interface offered with the machine (interface would be a Max5 patch probably)

any ideas? thoughts?

all the best,
julien