There are some things that cost very little that might be worth doing.
Try experimenting with speaker and component isolation - this can be tested for very little cash. I know the debate spikes vs isolators is ongoing, but it is cheap to test.
Get some big cork furniture glides at the hardware store and put them under your speakers. If they help, then better ones will help more and you can plan for the expense. In my case, isolating my speakers was a huge improvement (suspended floor and very heavy speakers). A better alternative is a cork pad meant for it
These are knockoffs of the original version
Vibrapods are inexpensive and surprisingly effective. Get a some and try them, they did nice things for my old DAC, but nothing for my new DAC.
Other than that, I agree with all the others about speaker and seating.