Bc2000 (for the BCF2000 & BCR2000)

Hi all

I have BCR connected in/out to a load of MIDI sources and running in S3 mode (to get parameter feedback).

When I move any endless encoder (havent noticed it on buttons) I can hear, thru my audio mixer, constant clicks.

I notice this isnt on all channels (only selected).

I thought MIDI cables themselves are current loops with opto-couplers to prevent earth loops etc.
And supposed to be twisted to stop noise.

And yet this BCR movement is creating audio in certain channels of the mixer.

So 
1] Anyone else ever experienced this from BCR2000
2] How did you solve it?
3] or any hints to track down where it is coming from.

I am working on isolating which kit allows the noise to propagate.
And checking my cables (gotta pick up the cable tester from a mate).

Oh I should check other than S3 modes too I guess.

Regards

Steve H