What exactly is textural density??

I don’t think this is about which voice or instrument has, in real life, more or less textural (tonal) density than another......
the point of quantifying or qualifying tonal density is to determine whether the reproduced sound does justice to the timbre of the sound being reproduced; whatever that might be.

Right to the point!....

Tonal and timbre density and his texture to the perceiving ears is the most important perceived fact to evaluate our own system and any system.,...There are others but without this one any system is more trash than audio.... The unbeknownst fact to most is that implementing  controls of the working dimensions of the audio system is on par with a good electronic design choice to begin with.....

Herb is describing a richness of sound and detail accentuated in some pieces of music and lost or retained by certain combinations of gear/cabling/AC purity, I think. Interesting to note the musicology of his terminology, but no need to fault him for his resourceful prose, even if not textbook.  I always enjoy his reviews as much for his prose as his clear lack of corporate sponsorship.  We also seem to have similar tastes, so it makes finding good value gear easier.

Good post and I agree. His attempt at a description points, once again, to the issue of harmonic truthfulness (timbre).

The use and better understanding of terms (“resourceful prose”) that are rooted in musicology to describe the perceived sonic qualities of audio gear is not only appropriate, but is something that, were it to happen more often in audiophile parlance, would reduce the level of confusion we often see in discussions like this one. I have always found it interesting and not a little ironic that there is often a disconnect between terminology used in audiospeak and well established terminology in musicology when, in fact, the actual parallels are many. After all, it is music that audio is dealing with, no?

More than a simple wise post indeed!

Thanks...

@frogman 
It would be great if more reviewers and consumers knew more musicology so they could help connect the worlds of music appreciation and audiophilia with greater accuracy and depth.  I feel like we're always just reinventing the wheel with our amateur descriptions.  An audiophile-focused glossary of music terms would be fun to use.