Hi kla4 & bruno123,
By "midi jack", I am referring to standard midi plugs (known as 5 pin din, I believe).
It's the kn7000 which makes the loud buzz.
Can drive my modules through my Tyros4 ok.
Have tried new cables but used the originals with Tyros and they are ok.
I don't understand what non-grounded outlets means - will have to look it up.
But the Kn7000 is plugged into a 6 way socket along with the tyros and the module and always worked ok before with this same setup.
The USB on the Kn7000 is really to connect to a computer but I wondered if anyone had used it to try and drive a module - don't want to do anything which may make matters worse.
Thanks for the interest guys - will post back if I learn anything new.