There have been a
number of new improvements for MC20 targeted at audio-only users. Read:
New Features in MC20. Many of the "big ticket" features of MC20 are actually audio features (like the WDM Driver, Link Timing, DSP over DLNA, DSP presets, etc).
The underlying audio engine is identical to MC19, though, so I suspect if you are hearing differences that it is either confirmation bias, or incorrect testing procedures.
In any case, this is not a productive question, so I'm going to lock this thread. If there is something specific you need help with, please feel free to ask specific questions.