The logo had the right hand side of the "D" as the left hand side of the "X", in DX7, joined together, as opposed to the final version which has the "D" and "X" as separate letters, as we all know, like this:

Well, I finally found an image of the early logo with the joined letters, to prove I wasn't going completely mad:

From http://www.kratzer.at, featuring the prototype CSDX, with the DX9 and DX7 logos in the style I remember.
Anyone know any more about this? Anyone have a prototype DX7 with the old logo? Anyone know if any ever made it to production, and why/when the logo design changed?
It's just something that always bugged me....