Korg Sigma synthesizer with a Kenton Pro-Solo.
According to synth historian Gordan Reid:
When Korg released the Sigma its design and a handful of its facilities put older preset monosynths to shame.
It was heavily endorsed by Rick Wakeman (who at one time replaced his Minimoogs with four of them) and also used by Keith Emerson.
Yet it never caught on, and within a few years had vanished. And that’s a pity because the range of possibilities contained within its weird architecture was huge.
Nowadays, its resale value can be very low, but who knows… if a bit more fuss had been made of the original rather than focusing on its limitations, there might have been a Mark II, and that could have been a very weird and wonderful synthesiser indeed.