some key changers may use mono (this destroys result)
 

I made a vogone file and used it at my place with disastrous results since I asked them to change the key for me. When I went ahead and changed the key myself using keyrite, and had them play that file, things were basically ok.

I experimented at home and have noticed that if I try to convert the file to mono sound, I can *****k the disastrous result. I wouldn't be surprised if this is what some machines do when they change keys. (The mixer I have at home does not have this problem when it changes keys)

Thanks for this bit of information
 

This goes to show that many problems users face when performing digital signal processing.

As you point out, when you used MTU's Vogone and Keyrite digital signal processing programs, all worked correctly as expected.

When you used your own key changer, it also worked properly. However, when you used an unknown key changer there were unexpected poor results. Go figure! :r

The only way to know for sure is to test on the target machine before getting on pickled on stage. :e