Last year I replaced my 20+ year old wobbly, glass-doored, solid-walled rollered cabinet/rack with an open five shelf Sanus audio rack. WHAT A DIFFERENCE!
The Sanus is 90# to start with, is filled with 60# of graphited steel shot (just like a big dead fall hammer), and I've got it topped with a 50# slab of Italian marble under the turntable. Each MDF shelf is independently isolated and the whole thing is spike mounted onto a concrete floor.
While I did a bunch of interconnect magic after the rack change, the rack change itself improved the sound quality to the point the She-Who-Must-Be-Obeyed accused me of getting all new CDs.
FACT: IF YOU DO NOT HAVE A GOOD, SOLID, ISOLATED SURFACE UNDER YOUR AUDIO COMPONENTS, YOU DO NOT HAVE THE BASIS FOR GOOD SOUND REPRODUCTION.