Yet another question :-) ....but if you don't ask you never learn imho!!!

I have connected my 5000 to my old (but much loved) PX7 piano via a midi lead. All goes well except that when I play the 5000 using the PX as a master keyboard the sounds from 'right 1' are less defined and have less volume than if I play the melody on the 5000 itself. Is there a setting I can alter to correct this?? I know next to nothing about midi (...well not just midi but hey!!!) and so used the preset on the 5000 for connecting to a px piano.

Many thanks for your continued help :-)
Regards as ever
Tony