Not that close to a sine wave, that's why I recommend the switch. Those vertical edges play havoc with the DCS carrier.
Z-Controller Fill Throttle
ZW-C Full Throttle
This waveform is much more "DCS Friendly"
As for passive mode, that jack on the DCS-RC really is straining to handle more than a couple of amps, I've already replaced several of them that melted down.