There is a difference between a theoretical filter curve and the real life implementation of that curve. The filters in HQP all have names and descriptions that can be looked up if you are interested in signal processing.
Miska/Jussi’s filters have two advantages:
They run on a general purpose computer, rather than the less powerful dedicated hardware in a DAC. His closed form FIR interpolator has 16,000 taps (delay line series module equivalents) compared to 2,048 in the Chord WTA filter;
They are designed by an audio enthusiast with extensive experience in signal processing (including SONAR).
Now you can read all about signal processing or Jussi’s professional experience online, but isn’t the real answer to this discussion to try the free trial and see how it sounds to you ?