Best treatment for speaker feet????

spikes all the way, but depending on how sharp they are and speaker weight, they may actually sink into the plywood floor and cause the speakers to not be level. In those cases, it's best to use spikes and floor saver metal disks under the carpet that contain the sharp spikes or adjust the spikes length to compensate for the amout it sinks into the plywood. At 80 lbs. per speaker you may get away without the floor saver disks as the spikes may not penetrate that far into the plywood. YMMV.

The Symposium Svelte Shelf looked like a great solution UNTIL I saw the price. $800 for a pair? Ummmmm...yeah...no...

I use a platform I made myself with the spikes on them. I have the same plywood under carpet and it works out great. I did experiment with the spikes on the speakers after that. The platform gave me a solid foundation coupled to the floor. You can play with de-coupling if you like after the platforms are put in.

The cheapest and perhaps sufficient approach would be just to get good big spikes, say, Audiopoints brass spikes. They should penetrate the carpet. Another possibility is 2" thick spiked maple platforms under speakers and spiked speakers. To possibly improve it further - Boston Audio Tuneblocks S for spiked components, that's under spiked speakers between speakers and spiked maple platform. I use them with my speakers.

Number of opinions of this = number of audiophiles present + 2. [ some are bound to be of at least two minds on the subject, as I am]. I use and sell the Star Sound brass cones, which work well; I have also used the FIM roller bearings which I also sell. I really like the SR MIGs also, haven't used them under speakers yet as the ones I have set up have their own outrigger base. There was a really good looking outrigger base with spikes for a not totally unreasonable price but the web site has disappeared and I fear they are gone. Maple or sandwiched MDF shelves should work; years ago I knew someone who was using grave markers, he called them "dead weights". With the exception of the roller bearings I like the coupling devices better than isolating ones; haven't tried all obviously; Ceraballs works well under components but haven't had them under speakers.