different velocity's / volume

I am using the mpc to trigger another device got it all hooked up but when it comes to playing back what I have programmed in, it plays at different velocity if more than one thing is playing at the same time, what could this be?
Rob

That may depend on what device you are triggering. What is it exactly?

akai s950, I am fine if each note is played at a different time but as soon as the hats come in and they go on top of the snare, it makes the snare go quiet, I cant seem to work it out!
ROb

worked out if I use the seperate outs this sorts it, cheerz