Regarding power requirements, I would add that in addition to room size, listening distance, and individual volume preferences, a very major variable is the dynamic range of the type of music that is listened to. Dynamic range meaning the difference in volume between the loudest notes and the softest notes.
Many and probably most pop and rock recordings are compressed to dynamic
ranges of less than 10 db, meaning that less than 10 times as much power is required to reproduce the loudest notes as is required to reproduce the softest notes. While many recordings in other genres, such as classical symphonic music, can have
dynamic ranges of 30, 40, or even 50 db. A 30 db dynamic range means
that 1,000 times as much power is required for the loudest notes as for
the softest notes. A 40 db dynamic range means that 10,000 times as much
power is required for the loudest notes as for the softest notes. And music having wide dynamic range will generally be played at levels such that brief dynamic peaks reach much higher volumes than the peaks of music that never gets much above its average level.
Which is one reason that like most recommendations for amplifier power that are provided by speaker manufacturers, SF's recommendation for the Venere 2.5 (40 to 250 watts) covers a very wide range.
Regards,
-- Al