I would say the amp. For clarity's sake, AVR, since that's what I've been assuming with the tests. While I think something has happened to it with the introduction of the line filter, the original increase in hum came with the Actives, which is what makes it hard for me to work out. What would you say made that hum at that point versus the gear I already had with the passive LFRs? Going with what I have now, by process of elimination the AVR certainly seems to be the big culprit. If I have all of the gear on with a source active (as in on, not necessarily playing content), the hum is loud through all connected speakers. If I turn just the AVR off, the hum is way quieter, though still there.
While I plan to replace my AVR, I'm not quite there, and I don't want to buy something new only to have the same behavior with the potential of it worsening.
