Hi Bob,
As you know, I don't claim to know much about music theory but you have me a little confused Surely a C7-9 chord would include a 'D' not a C# since D is the 9th note of a C scale. If I was to play a C7-9 then the notes I would expect to play would be C,E,G Bb and D. Since that's a bit of a handful, I would drop the low C and just play E,G,Bb and D, which produces much the same sound.
However, the KN7000 interprets this combination of keys as Em7b5 which I suppose it is! - quite a chords having 2 possible names........
Using my unorthodox method of fingering in my left hand, I could include a 'C' by bridging the upper 'C' and 'D' with my thumb!!
If a C# is included within the chord, surely this would indicate a 'b9' (flat 9th) ?? rather than a '9th', or have I got this completely wrong?

Just had another thought - maybe the '-9' part of the name is another way of describing a flat 9th? in which case that would account for the C#