"you can do so much digitally... If you really want things to sparkle, get it professionally mastered."

Most professional mastering is done digitally.

What you're paying for with good mastering is a pair of good and experienced ears, a pair of accurate and frighteningly expensive speakers, a well acoustically treated listening room, sophisticated processing equipment (usually digital) and someone who knows how to use it.

Oh, and nobody has satisfactorily defined "warmth" to me in terms that distinguish it from distortion of some sort. 30 years ago there was a lot of really bad digital kit because some of the problems weren't fully understood, and you could still get better sound out of a well-aligned Studer A80 or A800. Now any affordable digital recording system is better than any affordable analogue recording system, unless you actually need to use tape saturation as an effect.

So as a modern digital recording system adds nothing* to the sound, I'm not sure that "adding warmth" is going to improve things...

Anahata
* i.e. nothing within the audible range of frequencies, except a little pure white noise at a much lower level than normal tape hiss