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So I'd suggest moving the mod(s) out of the Kitty folder and replacing vo with ui.
It should also be noted that unless the killsounds are named separately for each mod (and even that has its limitations), they will not work together because they are trying to overwrite the same file.
Finally, the Source engine is very finicky with sound files because they have to have just the right settings, or they won't work. Therefore, I also suggest you make sure that the audio is in 44100hz, 16 bit wav format.