Pre 96 are logoless and then I think 97 late 97 was the logo version. The Sotto Voce came out a few years back in mid 2000's as a more plain version was demanded by consumers.
Sotto voce are with a faint logo as mentioned.....
I've used a few no logo Chris King headsets and i'm pretty sure they were all early stuff.....usually came on bikes in the early 90's as that is where i've seen them placed before but i'm happy to be corrected.