I was reading about Audiotechnica's new "Pure Digital Drive" headphone drivers here, and I can't understand how their drive scheme would be better than having a regular DAC feeding into the voice coil. It seems like the first curve they show, 'Analog Input to Driver' provides a smooth interpolation between the signal that would be more desirable than a choppy digital transition like they show in their 'Digital Output' waveform. I know the specifics of their technology is proprietary, but I was wondering if anyone here could better explain why this scheme is a good idea.
There is a DAC driving the coils, it's just that it's a 2-level DAC that works as a class D amplifier. The difference between 'digital' signals and 'analogue' signals is that in the former, we don't care about the exact levels, or whether the levels change a little between pulses. By that definition, this headphone drive system uses analogue signals, the digital to analogue converter must be consistent in the levels it provides to the coils.
A lot of what is written in that note is pure BS and audioFUD. However the technology works, and works sufficiently well in terms of audio that the differences between that and conventional good DACs are swamped by other considerations. Being class D, they will (should) be lower power consumption than a more conventional signal path.