Hello Ray,
Thank you for the astute observations of our Little Hiros. The larger speakers present a larger soundstage with a more refined upper midrange and lower treble due to the more advanced compression drivers and larger horns. The bass extends deeper as well due to the backloaded horn design of the full-size Hiros and the much larger Mark Audio main driver on the Hiro 6.5. We have a new Hiro 8 in the works that are a 3-way design: Compression/horn combo from 2K up plus a 4-inch Mark Audio main driver bolstered by an 8-inch powered subwoofer in a stackable cabinet design. It will be similar to our discontinued model BosuHiro but more refined.