LOOPING clicks when tuning

Allright , so i made a loop on a stringed instrument so i can play it as long as desired , a perfect loop , zero crossing and all , no clicks everything fine and dandy. Then i spread the same sound over the 16 pads in program mode and tune them so i get 16 pitches , then i notice when playing the sample tuned down or up , i get clicks on the loop point. Do i really have to sample 16 notes of the instrument and then use 16 samples on the mpc or is there another solution? I'd hate to do that cause then i'd have to record each note , then get a perfect loop on each pitch and load 16 samples instead of just one into the mpc memory ( and at the moment i'm still stuck with 16 MB (11.4 wave memory) and my memory get's filled really fast)
Greetz...