I have a lot of customers using Weiss DACs and have mixed responses on the DSPs in general. The D'Esser, like analog mode, is a mod and some people like and others just hate the concept. It undeniably works but ultimately via the removal of information.
The one DSP almost everyone seems to like is the crosstalk cancellation. It increases depth, clarity and coherence. It is like a simple BAACH dsp.