I posted before about receiving about 150 grungy albums and cleaning them with soap & water before I'd even let them touch my 'table. So, to keep them in some order, I stacked about 15 or 20 on each speaker on their sides, not on edge as they should be (my Snell B Minors are on casters) and lo and behold, the overall sound has improved. Seems tighter and more detailed. Maybe less cabinet movement and more floor coupling??
When I'm done sifting through this mess (about 1/2 of the albums are trash) I'm considering keeping the bad ones and leaving them on the top of the speakers. Now I want to experiment with some other heavy objects placed in the same locations.....my speakers are 105 lbs. each, so I thought they'd be fine on casters, but with this improvement, I'm thinking that I have a lot to improve on and a lot to learn about coupling. Talk about a cheap tweak!