The standing rule of thumb in electronic music is that having many really cheap synthesizers is better than having a single expensive one. Richness and diversity in sound comes by the different ways in which each synthesizer computes a signal. Yamaha uses FM —Frequency Modulation — for its synthesizing function. Casio uses PD —Phase Distortion. Others use an “additive” algorithm. Take a multitude of sources, blend them together, and you’ll get sound textured in the way real-life sounds are — impure, uneven, rich.
Combining sound generators, there’s no reason to have a keyboard on each, so the cheapest synthesizer module doesn’t. It is the multi-timbral Yamaha FB-01 (about $350), roughly the size of a hardback book. Some music stores that cater to electronic
