Rev 6AFF Audio Pro Modified (Rosenut). This inexpensive speaker has a superior built cast frame woofers with butyl rubber surrounds which will last 20 years and super lightweight titanium dome tweeters which have a special phase-correcting lens over the tweeter, as well the use of a ferro fluid dampening coolant in the tweeters magnetic gap to improve efficiency and dynamic range capability. The cabinet is heavy MDF board with bracing around the internal walls. What is crucial is that the dynamic efficiencies of the woofer and tweeters be similar, therefore the sense of bass to treble levels remains in timbral balance at very low or high acoustic output listening levels, which this modified speaker does incredibly well. Read more about Paradigm mods here