A lot has been gained in the last 20 years in the area of materials used in the manufacture of speaker systems. From the use of gold/rhodium plated, oxygen free copper 5 way binding posts(for a better connection), higher quality (tin foil/teflon film, polypropylene, polystyrene) capacitors for improved signal transfer, stronger magnets( barium/strontium ferrite, neomidium) for higher flux density, stronger and lighter cone and dome materials(carbon fiber, titanium, diamond) for less flexure/distortion, faster response. Denser, stiffer cabinetry to reduce resonance/coloration. There are a vast array of modern speakers that can play at very high SPLs, and yet sound like real music, unlike the Junk But Loud of old. Yes- the professional speaker manufacturers built some systems for home use, but the quality of the drivers/x-overs in those systems never approached that of their sound reinforcement equipment. The horns that were designed for projecting sound far into an audience, when used in a home environment, could generate a headache faster than a jackhammer with their peaky responses, and metalic resonances. Much has been gained/learned with regard to horn systems as well, and the old can't even compare with current designs acoustically(Acapella/Avantgarde). Of course the way we test/design systems has changed drastically as well. The proof is always in the sound though, and naturally: There are those that can't hear the difference, and will claim there isn't any.