A friend of mine, some years back, was totally convinced that the walls of his speaker enclosures flexing was causing them to sound "muddy." He tried several different materials by themselves or stacked, but wasn't satisfied. He ended up building the enclosures out of concrete, with the baffles made of a super-fine-grained particle board that was more resin than wood. He insisted that they sounded much better, though I couldn't hear much of a difference.
A few years later, he changed jobs and had to move halfway across the country and it was impractical to take the speakers along due to the weight. He removed the baffles, speakers and crossovers, then smashed up the concrete enclosures with a sledge hammer. Of course, he made new ones after reaching his destination.
This guy is the quintessential geek, and though some of his ideas are really out there, others actually make sense. One of his favorite statements concerning audio is, "If you love vinyl, you really need a tube amp." (BTW, for our friends outside of North America, read "valves" instead of "tubes." I call them "Glass FETs" myself.) He had his system set up so he could switch between a phono preamp with CMOS instrumentation type op-amps and one built with Russian-made ECC83/12AX7 tubes and I could definitely hear the difference there. The tube one had a "warmer" sound to it and there was some detail to the sound noticeably absent with the CMOS amp.
My favorite solid-state preamp is Discrete Class A, but then I'm old school.
