Shenanigans. I keep hearing people talk about bare oscillators that sound “rich” or “full”. Seems to me that’s just harmonics added by peculiarities in the waveform. And the A4 has more tools than most at shaping those.
But I’m certainly not into modular so there could be a whole world there I’m missing? I’d be forever in your debt if you could post some recordings of straight, plain DPO tones so I could hear what the fuss is about (and try to match it with an A4).