The use of vinyl veneer for the casement is by far the most common material in the industry. There is no sound difference between various veneer finishes, vinyl or otherwise. The trick to loudspeaker enclosure design is to not have the cabinet creating any sound of its own. This is accomplished by core material thickness selection and bracing that compliments the maximum energy created by the driver. Axiom is extremely experienced at proper cabinet design and hence the great performance.

The use of damping in the Axiom products works in conjunction with the cabinet shape. The damping placement inside Axiom speakers is directly behind the woofers. This placement is very favourable from the point of view that the sound waves inside the cabinet are travelling at their fastest speed in this location. Further to the damping the asymmetrical cabinet shape also aids in reducing the internal sound waves, in fact more so than the damping itself.

The use of metal for cone bodies is definitely "tricky business". Axiom has been experimenting with, and using, metal cone driver technology since 1985 in order to extract the enormous benefits of this material and avoid any of the issues you were asking about. We completely avoid any resonant problems with metal drivers through the design of the drivers themselves.