Some selected heavy woods:
Snakewood (<i>Piratinera guianensis</i>) s.g.= 1.3
Lignum Vitae (<i>Guaiacum officinale</i>) s.g.= 1.23
African Blackwood (<i>Dalbergia melanoxylon</i>) s.g.= 1.2
Brazilwood (<i>Caesalpinia echinata</i>) s.g.= 1.2
Kingwood (<i>Dalbergia cearensis</i>) s.g.= 1.2
Cocobolo (<i>Dalbergia retusa</i>) s.g.= 1.1
Macassar Ebony (<i>Diospyros celebica</i>) s.g.= 1.09
Ipe (<i>Tabebuia serratifolia</i>) s.g.= 1.08
Tulipwood (<i>Dalbergia frutescens</i>) s.g.= .96
Notes:
--There are most likely more woods in this category, but I found these fairly readily by thumbing through World Woods in Color, William A. Lincoln
--Some of these woods are known by multiple common names
--Some of these woods have more than one Latin name (bummer--makes life really difficult)
--Most of these woods are medium to dark in color, hard (not the same thing as heavy), and beautiful (except Lignum Vitae, pretty drab stuff). They're also comparatively rare and expensive. With the noted exception of Lignum Vitae, any of these woods would be a beautiful veneer for speaker cabinetry, although there are many cheaper, easier-to-work woods that are also beautiful.
--Lignum Vitae is most likely the wood that web site is referring to as Ironwood, but as every continent in the world has at least two or three trees known locally as ironwood (got some in my yard as a matter of fact, but it isn't Lignum Vitae), without the Latin, we can't cross check
--The reason I included Tulipwood is that that is what I suspect the wood used for the legs actually is. Note that it (like Cocobolo) is in the Rosewood family and grows in the same general areas, but it's much lighter in color and doesn't have the dark streaks that Colobolo has. It's a beautiful wood in its own right. I've got a plank waiting for the right day, myself.
Note that it's common practice to sell one wood as another. Much "Mahogany," for instance...isn't.
Grey