I've often wondered, since more density for enclosure material is generally recommended, what speakers would sound like in concrete or granite enclosures but it probably wouldn't sound good at all. You refer to the friend who used a dense "sandwich" material and the bass sounded quite dry. I suppose the cabinet material does have to respond and improve the sound. I have an older pair of KLH tower speakers along with a pair of Dayton Audio 6 1/2" AIR bookshelf speakers with AMT tweeters and a Yamaha 100 watt per channel receiver and it sounds awesome to me. One of your drivers probably costs more than my whole setup. KLH went out of business but now they're back and They are a little pricey. Mine were inexpensive but I've been very pleased with them.