There is no class d amp that will sound like a class A or tubed amp, sorry.The issue here is distortion- it is distortion that causes tube amps to sound 'warm' and 'lush' and its distortion that causes traditional solid state amps to sound 'bright' and 'harsh', especially at higher volumes.
Class D amps do not make the same sort of distortion as traditional solid state. As a result, the generalization in the quote above is false. A class D amp will sound like a tube amp if it makes enough 2nd and 3rd harmonic distortion to mask the higher orders, even if its THD is two orders of magnitude lower than the tube amp to which it is being compared. If there are non-linearities in the encoding process, you do in fact get the lower ordered harmonics as the primary distortion. Just one example...