In practice, all audio converters are modulation converters of some sort, because it is simply too expensive to achieve the high AC linearity wanted at the required sampling frequencies with other kinds of converters. This already relaxes LPF requirements.

In practice, signal quality issues are usually layout and supply issues, not problems with the converter itself.

In practice, the speakers and ears are the worst parts with the largest non-linearities and a frequency response that looks like a nuke test area compared to the FR of the converter. Of course, in the case of speakers, we have concluded that we want them to have their own sound, because neutral speakers are not possible.