Doki wrote:

Has anyone got any experience and suggestions of DIY methods of
isolating speakers from the floor? I'm looking to do it to reduce the
amount of noise transferred through the floor to downstairs, rather than
as a method of altering sound quality.
If the problem really is transmission of vibrations then decoupling the
speakers from the floor with a layer or two of carpet and a bit of mass
like a paving stoneon top would help. Assuming, of course that you can't
fix them to the wall.
Cutting the low frequencies might be a better approach.
At the end of this road of course lie headphones.....