This is pretty cool for rich people, for whom buying half a dozen US$300 synthesizer modules is no big deal — the kind of people who buy new mechanical Rolex watches every year; but it seems to me like anyone with an income under US$1M/year might be better served with SuperCollider or Pure Data (free) running on a netbook (US$300) and maybe a MIDI keyboard (like the Keystation 49, US$100) and a MIDI or USB knob box (like the nanoKONTROL2, US$60).

SuperCollider and Pure Data already come with an awful lot of the modules you can buy as analog hardware. You don't have to buy them. You can just use them.

Now, if we were talking about an electric guitar or something, this comment would be sort of out of order. But the whole point of modular synths is that you want to spend time fiddling around and plugging parts together. If you want to do that, come to the software side. We have WAY BETTER PARTS to plug together. You can make them sound like anything, including analog synth modules. And you can get inspired by how other people plugged them together because you can upload your patches to web sites. It's nothing less than a vastly improved substitute to analog modular synths.

Back in the 1970s, computers were too slow to do much in software. Even the famous Deep Note, from the 1980s, used hardware oscillators under computer control (although it's a fantastic example of the expressive power software gives you). A PC in the 1970s might be able to manage 300,000 instructions per second, and maybe 10,000 floating-point operations. Now you can do literally ten billion floating-point operations per second on an off-the-shelf CPU, a million times faster, or eight trillion on an off-the-shelf GPU, almost a billion times faster. This brings a lot of amazing stuff into reach that wasn't before, including even things like RF modulation and demodulation.

RF downconversion, though, still takes analog electronics. Computers still aren't fast enough.

I've done some work with Diego Alberti on real-time music synthesis on a microcontroller. Because the real-time audio synthesis wasn't taxing enough for the CPU, we decided to generate a composite video signal in software visualizing the waveform, too: https://github.com/kragen/ar_bytebeat

He carried this work forward, and it is currently on exhibit at the +CODE exhibit at the Centro Cultural General San Martín until the end of this week, if you're in Buenos Aires.

With that kind of thing, hopefully you won't have to spend US$300 on a netbook to experiment with software synthesis. Check out jarmitage's comment at https://news.ycombinator.com/item?id=10540209, which mentions running Pure Data patches on a computer embedded in a guitar pedal!