Craigl59 7-16-2017I would respectfully but emphatically disagree with the use of the word "required." A more appropriate interpretation, IMO, would be that the specification of "400 watt power handling" provides a rough ballpark indication of the maximum amplifier power capability that is recommended as being reasonable for use with this speaker.
There’s another way to look at power and the DIs. Eric specifies the power handling of the speakers at 400 watts. That’s what I use to judge how large an amplifier is required.
Also, as Mac alluded to, for a given amplifier type and topology it can be expected that everything else being equal more amplifier watts = more amplifier $. Therefore for a given amplifier budget paying for watts that will not be utilized would in general mean that a higher percentage of that budget than necessary will go toward watts rather than sound quality.
One of the reasons I chose my Daedalus Ulysses speakers, which like the DI have a very benign impedance curve, fairly high sensitivity, and high power handling capability ("recommended power 5 to 300 watts, peak power 600 watts +") is that I wanted the majority of my amplifier dollars to go toward sound quality, rather than watts. And even though I frequently listen to well recorded minimally compressed classical symphonic recordings which reach brief dynamic peaks of close to 105 db at my listening position, I have been very happy with my 70 watt VAC Renaissance amplifier. And perhaps its 30 watt smaller brother would even have been suitable as well, but I wanted to be sure that the margin between necessary power and power capability would be comfortable while not being excessive.
Regards,
-- Al