weird interference from DR-880

[cortexx]

scenario is as follows :-

DR-880 midi plugged into a roland vsynth and then into a korg ms2000B

Running drums out on midi port 5 to the vsynth and bass line to the ms2000b on midi port 3.

when i listen to the output from either synth i can hear what sounds like midi interference noise in the background ( kind of like a gated whitenoise generator ) .

Tried changing midi cables , patch cables , one synth at a time etc and i cant figure out where the noise is coming from .

Is it possible for Midi signals to bleed into the line outs of my equipment ?

regards

Paul