Thanks Ian and Alan,
Besides the good performance you are getting Ian, it sounds like a good buy at £34 just to do away with the disconnecting/ connecting R/box between D/top and L/top. I'm never keen on disturbing things that are operating as they should be, - leave well alone being my general principle.
It seems the decision on whether to incorporate a filter should be made when the performance of the Micro in my environment has been considered.
regards,
Syd.