I've never heard 009 but I did own L700mk2 which I've read are in general 90% of 009 when using Stax amplifiers. However 009 are supposed to be much better when using Headamp BHSE or KGSSHV and I was using Stax SRM-007tII. I've also read that 009 are brighter and more neutral and L700 are warmer and not as picky when it comes to equipment.
First of all, KSE posses more weight in general. They have much more powerful bass going all the way down to the bottom combined with a strong impact and great physicality. The L700 bass is shallower, there is generally less of it, it is not that varied or so palpable. The midrange in KSE more forward, properly weighted, but not soft and not plush. The L700 are gentler and more organic on this subject, but also not as direct. Treble is more pronounced in the Shure, very resolving, without extraordinary aggression, but it is also no as smooth and refined as in the L700. Stax'es seem more natural here, conveying even more information in a more calm way. The L700 has a softened attack which allows for pleasant and fatigue-free listening, while the Shure is more tangible and much more engaging. KSE are not as ethereal as Stax, and yet they manage to maintain their purity, speed and transparency, adding to this greater genre versatility, more punch and weight. The L700 have a larger stage, although they deliver the sound not so directly and from a greater distance. Moreover, they have even higher resolution, they are calmer, more organic, and are more sophisticated, while the Shure's are more exciting, contain more energy, allow for closer contact with music and even physical contact with it.