On the draining of resonance.....

Ommmmmm. Of course you would ask me that! My wood blocks I was using on my old shelf (and when I say old, I mean like 175 years old!!) don't fit on my new shelf, so my turntable is sitting on the ground, which is OK, because the ground is a concrete slab over 300 tons (literally, don't ask) of crushed rock. My old Thorens TD150mkII sounds best in this configuration sitting directly on the floor on its little rubber feet. The bass is from middle earth somewhere. In my rather flexible old wardrobe, my CD player, table and amp all sounded better supported with cones on a large wooden slabs that were isolated from the actual shelf (purely home brew) as described above and in the images from Mapleshade. If you have a concrete basement floor resting on a large mass of rock, I might recommend trying your turntable or disk drive on their stock feet sitting right on the floor. I haven't tried my amp in this configuration. If/when I reconstitute old setup, will post photos.

Tosta, no.
What I am saying that if it still worked and was all you still had today you should not be distressed about it.
Easier said than done, but that's the goal .

I realize my suggestion to put gear directly on a concrete floor is something of a side light given the original post, and could be perceived as contrary to my earlier advice, so let me praddle on a bit further.

The conditions that made me resort to the more heroic isolation and "draining" were I think more typical of what others face, a shelf system on a wooden floor supported by joists. Everything flexed, and flexed further with loud music playing. My experience was that the biggest difference was made with the large, heavy wooden board directly under the piece of equipment, I assume because it adds resting mass and absorbs both external and internally generated vibrations. The second biggest difference was derived from using small metal cones to connect the equipment to the board. I have not used large brass cones, which some swear by. Without the large wood, the cones can sound bright. With the wood underneath, the cones added clarity without brightness. Isolating the large wood from the underlying shelf with something pliable like sorbithane dots added value, but proportionally less than the wood and the cones.

So why does the concrete floor work so well with my turntable (well enough to put up with bending down to change records)? I do not think that much internally generated vibration is goining into the floor. I think the value added is that the floor imparts diminishingly low amounts of vibration back to the table at any volume level or external input short of an earthquake. Imagine a 300 ton turntable platform. This kind of stability works effectively in concert with the sprung platter and arm of the Thorens. I haven't tried this with my amp yet, but am convincing myself as I write this that I should.

kn

There's no arguing with bedrock. Yes, newer homes have engineered floor joists that flex quite a bit with foot traffic. KN, are you in the basement, or on a slab?

Yep the construction in most good quality newer homes is good when it comes to earthquake tolerance but bad when it comes to interacting with your hifi as well.

Long live Bedrock!

You have to isolate your speakers from interacting with teh floor otherwise to preserve detail and clarity. Like isolation pads used under a subwoofer (I place my floorstanders on Auralex Subdude isolation platforms) or monitor stands also designed specifically to isolate monitor speakers from what they stand on (I use Isoacoustics pro monitor stands ).

If you have your speakers sitting directly on most modern suspended plywood construction floors, you are doomed to mediocre sound until you get some form of isolation in place.