Brian, I used to play a KORG Delta and a KORG Poly 61. I also had an ARP 4 Voice Piano, KORG EPS1 and a Moog Prodigy. Back in the early 1980s, I asked a service technician to hot rod my Delta with additional modulation waveforms (internally wired to the audio output) and an he also installed a modulation intensity knob. It was real cool - great effects. Years later, I needed money so I sold the Delta. It was a versatile synth for its time.