Originally Posted by
davef
Adding a subwoofer absolutely does NOT increase the sensitivity of any speaker, regardless of whether or not you high pass the speakers. It is impossible to externally increase the sensitivity of a speaker.
What adding a subwoofer and high passing the speakers does do, is free up some amplifier headroom so you might gain a small bit of additional maximum volume levels.
With an average volume level of 77dB, and then accounting for +10dB of headroom (music), you need to be able to reach 87dB at your listening position.
To reach this level, the Sierra-2EX will require approximately 3 watts (accounting for typical room gain) With that in mind, I would say you are safe with the Aegir.
Hope this helps!