> Can someone give me an example of an application that requires
> a perfect sine wave Will a perfect sine do special things when
> used as an FM or AM source I don't think there are too many
> people doing additive synthesis, but I can see how it would
> benefit from perfect sines.

In DX7-style FM synthesis perfect sine waves are important. I once
used a softsynth, where second order parabolic functions were used as
approximations for sine. The results were not satisfying, until the
issue was fixed by using higher (up to 8th) order parabolic functions.

Maybe ring modulation and frequency shifting benefit from pure sine
too.

My Cwejman VCO-6 and VCO-2RM make good sine waves by analog
standards. They look perfect in my oscilloscope. However, one can
hear, that VCO-6 has some "buzzy" higher harmonics present. It is not
immediately noticable though. On the other hand, VCO-2RM draws
attention to more pleasant lower harmonics. I would say VCO-6 is
closer to perfect sine.

Z3000 sine certainly doesn't look perfect. If people like it, I would
guess it is not too buzzy.

Skewed sine is is different from triangle or filtered saw and can
sound like a vintage Theremin. It should get progressively more
skewed (brighter) at lower frequencies though.