A 3" wide x 90" long 8u Al midrange riggon with 0.6T could reach 103 db/watt

Custom DIY bridge topology amps would be necessary to direct drive the 0.1-0.2 ohm midrange ribbon. 32 watts Class-A would seem adequate, and a high current delivery challenge

Five 15" woofers in parallel could match the 103 db/watt of the ribbons. A high 0.94 Qts like the Lambda Dipole woofers would save some baffle boost power. Should reach below 30Hz in most rooms.

Since this is Ultimate...an array of sealed bipole woofer stacked pairs would pressurize the room for 16Hz-30Hz.