saw this video earlier today, and thought it was pretty neat. probably more expensive than an attenuator box would be; especially used, to equip a normal person's rig. although this would be a good option for somebody like me who only has a single 1x12 cabinet in an apartment.
[VIDEO]http://www.youtube.com/watch?v=BJP2PosH9fk&feature=player_embedded]YouTube - Eminence FDM Reignmaker Speaker[/VIDEO]
They are a great idea.
but only really work in open back cabs and don't actually make that much of a reduction
A weber Mini Mass would be a much better option and far far cheaper.
However i do love Eminence speakers and will probably buy one at some point