Said it before and I'll say it again:
If you don't have any way to detect an improvement, let alone confirm the manufacturer's technical claims about what the product does --
Do you really need it
at all?This goes for absolutely anything, not just this. Does your phone provider really have the coverage they claim? (Actually they might. Someone in a claimed coverage area would be very vocally disappointed to see they actually aren't.)
Does your car really have the mileage claimed? (If it has a mileage readout on the dash, is it truthful? Ultimately, you can measure average based on logged miles and fuel purchases. And they are held to federal standards, so it's unlikely they'll say anything grossly out of whack with the real thing.)
So does the audiophool filter really do anything?
It might not. An audiophile isn't going to know the effects of something so abstract. They mostly use amplifiers with iron-core transformers, anyway, which do a good job filtering and absorbing most mains trash to begin with. The filter needn't do anything at all, to still have a filtered environment, even still assuming that the circuit is ultimately sensitive to line noise.
But if you want to use that "filter" for something that actually needs filtering -- and whether it even needs it, can be determined in exactly the same way -- how do you know it will work?
Now, manufacturers of [real?] electronic filters, provide curves showing their performance. It's important to note: these are made under specific conditions, which are rarely matched by mains wiring and plugged-in appliances. But it's a start at least. The curves depend on the environment the filter is connected into, so one must carefully consider the application, too.
So, how do you know? If you've been picking up pops, buzz, spectral lines, etc. that are definitely coming from the line (they go away when filtered properly, or, uh, powered from an inverter maybe -- or a crummy automotive inverter makes things that much worse), that's a start, if not necessarily a good one! If you're doing power quality analysis and directly measuring noise, that's pretty much the end of that. But, if you aren't sure at all, in the first place? Reasonable enough to guess no.
Tim