I filter the whole power strip, assuming the total load doesn't exceed the ratings of the filter. I purchase mostly the 15 amp filters, so that is unlikely, though I have some 5 amp filters.

These power strips are tricky. I have one that looks like a power strip, but I noticed in the fine print it said something about "clamping voltage". Turns out it was some sort of surge protector and was sucking the X-10 down.

My expereince has been that most surge protectors have a negative effect on X-10 and should always be filtered. Sometimes the effect is not great, but every little bit hurts. I use an ELK meter to double check what something might be doing to the signal.

Deane