Speaker spikes-worse sound-what gives?

I recently bought a pair of Silverline Sonata lls and set them up in my family room (20x20. After some weeks of finding good positioning, I screwed in the spiked feet that came with them only to find a very different and somewhat worse sound. The base not only tightened but really became thin although the top end opened up a bit. The live sounding D. Krall now sounds like she is coming out of a box. The room is heavily carpeted wall to wall. The rear wall has cedar planking on it. The one wall that has windows is covered with heavy drapes and honeycomb shades.

I know the easy answer is to take them out, but I thought that spiked feet always improved the sound.

What gives?

rest of system is EAD Ovation, Aragon 8008 amp, Moon Nova CDP. (System is a little bright but not harsh. Tried using Red Dawn ICs and speaker cable but made it too bright, harsh and analytical. Before the spikes)