What is your favorite material for loudspeakers?

Rodman

Tung Oil is good stuff. Hand rubbed to put a little love into those speakers. The music gods are smiling on you.

You are correct. The best cabinet would be no cabinet. That is clearly why planar speakers over the years have had an edge over box speakers. Of course there are problems with that as well. di-pole sound brings the back waves into the picture and encourages you to bring those speakers out from the rear wall more than you might prefer, then there is the issue of controlling the woofer. I think I was just reading a review of a speaker that does that with electronics. That makes my eyes glaze over...and my head to explode...

We will see where all this technology takes us.

Mr Sounds- Yes, Tung Oil is great stuff and when applied with the bare hands: The body heat opens the grain a bit for an even deeper finish. Excellent way to bond with whatever you are finishing(gun stocks, audio cabinetry, etc). No problems with my planars and woofers. I've been actively bi-amping my systems with a pair of transmission line woofs for over 28 years now. The TLs can now stay in the corners(where woofers belong) and are aligned in the time domain by my TacT RCS 2.2X. I've always used TLs with my planars because the cone is basically unloaded, and can move fast enough(with a high slew rate/high damping factor amp) to provide a seamless crossover point. Do you ever spend any time in Indianapolis?

Concrete blocks? Were they sand filled?
I was speaking to a system I saw once where the speakers were poured in place. I suspect the chimney block effort was sabotaged by the front/rear panels.
ALL concrete is the way to go! A couple inches of Portland will never rattle.

I saw a pair of Usher monitors and stands recently with what appeared to be largely marble construction, unless it was a synthetic material of some sort like that stuff they use in countertops (Corian?). Very pretty and very heavy!

Magfan...Chimney blocks have no voids to fill. Agreed that concrete won't rattle, but it will ring, and at a low frequency.