I believe that spirit energy can travel through anything. They seem to have the capability to be in more than one place at any one time, because time and place as we know does not apply to them. They can implant a message onto any material that has the capability to record, whether it is your mind, recorder, tv, crystals or wood. I do think though that you have a better chance of receiving their impressions when you are directly asking them for it. No one wants to talk and not be heard not even the spirits. It is always possible that they directly give us the messages and we in turn imprint it onto one of these medias, or assist them somehow to do this with our energy.

              As far as the power drain that usually happens to equipment, it may be a manifestation resulting from the entrance or exit of the spirit energy into our plane. Maybe when they enter into our world it is like an attraction to where a source of energy exists either electrical, magnetic, or our minds, or a combination of them- Kind of like a magnet. I would be interested in any theories on effects of a controlled stable alteration of our time and space from another dimension.

              When we have this power drain on equipment don't some of us also experience a drain of energy ourselves. If we are empathic and connect to others we experience a draining of our energy if we permit it.

               I am an RN and this occurs frequently whether dealing with non spoken words from patients and families or assisting the dying to transition. So perhaps in the spirits attempt to communicate to us this is why power drains occur, it is that certain place or connection or state that has to exist be it in time or our minds that creates it.