Biggest audio hoaxes


Often when people discuss audio, they talk about "snake oil" or "hoaxes."

It's pretty typical to use the term hoax as a tactic against another who disagrees with one, or holds an unusual opinion or vouches for something which has not been verified. That's not what I mean by a "hoax." 

By "hoax" I mean an audio product or claim which has been pretty definitively disproved. Maybe not to everyone's satisfaction, but to common consensus.

So -- with that definition of hoax in mind, what are some of the biggest audiophile hoaxes you've heard of?
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@sokogear  has it right.  I tried a Symposium Acoustics Segue ISO platform and rollerblocks for my turntable and was astonished at the improvement.  I have since added rollerblocks for all of my electronic components and also got their Foundation Rack Ultra.  For my new amp on order (should arrive in a few weeks) I also ordered their Ultra Pro Ampstand, Stealth.  Vibration drainage, which is taking the vibration problem out from the component, is THE way to go.  No hoax at all, it works very well. 
@vladtheimpala,
A CD is the name of a slim round plastic silver disc that holds recorded music & allows audiophiles to enjoy "perfect sound forever", when of course they are not listening to the much better sounding slim round (usually black) 12" vinyl discs they were supposed to replace in the 90's.  
It's interesting to see the positive statements about springs now that some have adopted their use and heard the impact they make. 
Interesting in that those of us using suspended tables have either known or heard the affects
for decades......yet the negatives are always eschewed by those that felt because they could not level and set it up to bounce easily that its flawed. Its not a dig or a bias as much as an account of why marketing has so many victims of bad purchases that don't fit the buyers needs or skill set.
Lots of grandizing and marketing hype and overreaching unproven bs in this hobbie but others purchases are also just as infected.
A lot depends on the system, the room and more importantly the bias, wishes,  expectations and beliefs of each individual user and the voices they accept as correct (reviews ,personal or pro).
I,ve always felt people should listen for themselves not listen to someone else's biased opinion of what YOU should like. The biggest hoaxes always have the one element that far outnumber the charlatans  and con artists out there ......a captive gullible  audience .....
Like anything related to a purchase... trick is knowing what you need for what you expect to do or what really needs attention. Often the biggest hoax is being sold what you don't even need .... but leaving the store convinced you did...
Remember those rare dealers that would take the time backed by knowledge and budgets to show options for what YOU wanted , or needed . Not what they needed to move for numerous reasons. 
For me personally...  (generalizing) the biggest hoax is the idiotic belief that say 6000 gets you 95% of the perfect sound ....but the last 5% is another 44,000 🤑..... Take vinyl as an example...
The last 4 of that 5% AND the first  50% of the 95 % will always be the knowledge and skill and ability to get there. Second biggest hoax....is that by the time we can afford the last 5 %....the belief you still have the ability to hear it....🤦‍♂️