And this is why Watt is a poor substitute for volume, because speaker sensitivity is more important. Every energy doubling (50W => 100W) is just +3dB, and you'll loose some of that due to power compression at the upper limits. A speaker with 76dB sensitivity compared to one with 107dB is quite a different experience when fed 10W. Reproducing ~110dB of acoustic power is not particularly difficult, except for the lowest frequencies which might either require high electrical power rating or impractically large horns. Some people build horns as beds to make them fit into their apartment: http://www.hifi-forum.de/viewthread-188-2426.html