Good spikes on floorstanding speakers do work if the mass of the speaker is great enough to keep them firmly planted(unless your floors are creaky and resonant).
Throw rugs and plush furniture do work to calm a lively room.
Good (not necessarily expensive) power conditioners on things that spin work.
The cost of most tweaks far outweighs the benifit though. Even the tweaks that do work only improve the sound relative to the capabilities of the equipment. Careful placement of speakers can make a modest system sound quite impressive and enjoyable though.
Throw rugs and plush furniture do work to calm a lively room.
Good (not necessarily expensive) power conditioners on things that spin work.
The cost of most tweaks far outweighs the benifit though. Even the tweaks that do work only improve the sound relative to the capabilities of the equipment. Careful placement of speakers can make a modest system sound quite impressive and enjoyable though.