[quote name='polyrythmmm' timestamp='1367924002' post='2070993']
Apparent volume of tube watts versus SS, and how this manifests itself in the arena of driver calculations... ? ...
[/quote]
Watts are watts, voltage is voltage, so apparent volume doesn't figure into driver calculation. The reason valve rigs sound louder than SS for a given wattage is down to bandwidth limiting (less lows so less power needed, leaving it for the important stuff for hearing), compression (very top peaks are lower, so louder on average), and harmonic distortion (added harmonic content adds impression of loudness, and bigness to the sound without needing more power).