Iridium is an imperfect masterpiece. Despite the significant complexity of the available synthesis algorithms, sound shapers, audio effects, etc. the UI never feels cluttered or overwhelming, and it often leads you to the right place if you pay attention. Synthesis flexibility is as good as it gets - after six months of ownership and hundreds of patches created, I still feel like I'm at the surface of the sounds Iridium is capable of producing. Even synthesis methods that don't appear to be directly included (ex. multiple operator FM) actually are, in the form of kernels that allow you to define 8 oscillators (wavetable, granular synthesis, or VA) with independent amplitude EGs within each of a voice's 3 oscillators, and to define modulation (phase FM, true FM, etc) between them and even in feedback. The downsides: CV interaction works well, but unlike Hydrasynth, Iridium can't trigger an envelope from an external gate (too bad). The mod matrix is remarkable and powerful, but it can be clunky to set up a new modulation
(again, vs. Hydrasynth's shortcut mechanism, Iridium leaves something on the table here). Browsing the patch library is painful, and sample management even moreso. But! But. The sounds it makes are simply incredible. Once you click with it and start to figure out how it wants you to work with it, you may also find yourself forgiving Iridium its little frustrating issues because of the incredible sounds you are able to make with it.
