So to refocus my question a bit. My interest is could there be any possible harm caused to my system by using the passive Furman line conditioner? If anything, in terms of sound quality everything is fine, no hums, sizzles, or noise in the system at all. As far as I can tell everything sounds just fine in terms of high fidelity. So having heard that these devices can increase impedances greatly I want to make sure they're safe to use. Hopefully one of the AVA people can give me a definitive answer to that question, because beyond a doubt there's a lot of mumbo jumbo out there which I can't decern the truth of.
Don't create a problem that doesn't exist. Only deal in facts, and don't listen to what people post. Common sense can often help you discern if something is true or bullsh*t. If power conditioners posed a problem, you would find a ton of research articles on it, Consumer Reports would warn the public, you'd read horror stories all over the Internet, some brands would be bashed, electronics manufacturers would urge buyers not to use them, there would be massive recalls, etc.
Of course, like anything else, if you buy a cheap quality product, you get what you pay for. For audiophiles, a decent power conditioner isn't cheap. I'd say $1,500 is a good starting point (and that's a used price).