If you can only afford conventional wood or composite bookcase style furniture which is not audiophile approved, try the simple expedient of VibraBlock Constrained Layer Damper on each equipment shelf.
Available from Machina Dynamica, this sometimes is needed on only one or two different horizontal portions of an equipment support structure. You can usually hear the improvement increase in increments, and with damping devices in the unlikely event you pile too many onto a structure your music may begin to sound less wonderful, or over damped.
The horizontal surface supporting each loudspeaker is equally important to be damped. If you use speaker stands which do not provide horizontal space for a damper next to the speaker, then apply onto the base of the stand, or the floor.
I find it's more natural sounding to me when the support surface is damped rather than putting any damping on top of a component. Just a matter of personal perception.
By the way, this extra step can even be used to upgrade some audiophile approved racks.