In my opinion, the best tweak is ensuring the backside of all of your audio components face towards true magnetic north. The results are “jaw dropping”. As the magnetic North Pole moves, you will have to make adjustments to your components placement.
What’s your vote for the most ridiculous, overpriced, and useless tweak?
My vote: Furutech Outlet Cover 105 NCF $220, with “special crystalline material that has two “active” properties.” https://www.thecableco.com/outlet-cover-105-ncf.html