Don't know what the OP meant by describing Ma's sound as "thick and immutable." "Thick" means something to me in the context of a cellist's tone, although I wouldn't use the word to describe Ma. But "immutable"? Ma's sound is "unchangeable," "fixed," "permanent" or "eternal"? Uh...what?
Ma is ubiquitous, that's for sure. He's a force of nature, with fingers in many pies: film projects (check out the set of DVD short films set to Ma performing the six Bach suites), the Silk Road Ensemble, Brazilian tango, his work with Bela Fleck and others in the Americana genre...it just goes on and on.
IMO, the choice of performer will vary with the work. Ma's Bach Suites seem to me perfectly executed and...well, somehow less than compelling. I can't say why. Starker's early recordings of these are the gold standard, I think (the ones on Mercury LPs). But the performance I most often choose is Zuill Bailey's. Unaffected but passionate. Again, however, the work will dictate the performer, and this applies even within a single "work" like the six suites. Bailey is my favorite for the great first movements of numbers 1 and 3, but no one can touch Starker for the amazing Prelude of number 6!
And for the Beethoven cello sonatas, Starker and Buchbinder are just about perfect together. There are a couple of moments in the final movement of Op. 69 where an ascending or descending scale begins first in one instrument and then shifts to the other. A cello and a piano have such different timbres, and yet these two performers are in such perfect accord that they reveal Beethoven's insight into their commonalities as human beings, as if man and woman were two voices but one soul. (Both performers are male, but the voices of their instruments are at least as different as a man's is from a woman's. No idea which is which!) It's almost as if a single voice carries the extended scale.
If you are willing to take your Bach tweaked, try Matt Haimovitz. He likes to play in bars and jazz clubs, and resisted recording for a while, claiming that, for Bach, every live performance would have been differently inflected. This makes his recorded performances of the six suites very quirky, sometimes eccentric. (He also has recorded popular music, including a cello version of Hendrix's "Star Spangled Banner"--and "Purple Haze," for that matter--that are pretty astonishing.) And then there's Gavriel Lipkind on SACD. Very idiosyncratic, to the point of frequent excess. But worth a listen, and brilliantly recorded. The packaging, too, is unlike any other CD I've ever seen, in a good way.
As for vola da gamba, try Paolo Pandolfo. Exquisitely well recorded. And--although by no means finally: try Susan Sheppard for Suite #6. She performs it on a five-string cello, which is the insrument Bach wrote it for (it's the most virtuosic of the six suites, and devilishly difficult on a four-string cello).
