I would add "continuousness and coherence" in the sense that an unmusical system can make it sound like the music is being played by musicians who don't quite gel together and can't play "in the pocket".
That's not an exclusive description, however, since I also find etched sounding systems to be unmusical i.e. systems where the components emphasise the leading edge of notes but are harmonically lean or thin. Such systems can be coherent, but tonally, they don't sound real.