Don't forget that KiX can also play .wav files with the PLAY feature.

As for finding more .spk files that might prove to be a bit more difficult. A quick search on Google didn't come up with too much. Perhaps a more refined or deeper search will come up with something.

This won't play with KiXtart that I know of but since it applies to the built-in speaker I figured I'd go ahead and post it. (The midi one plays from sound card, not speaker)

Wizard Master Control Program (for midi)
http://www.wizardmaster.com/bludgeonsoft/wmcp/index.html
 
0303 (for speaker)
http://www.wizardmaster.com/bludgeonsoft/0303/index.html
 
But using the UDF should work just fine especially for a quick clip. You can show the player or hide it at your descretion.