Sorry Mapman, your comments are confusing to me. The sensitivity spec can be deceptive, however, nothing to do with frequency since it is measured using a 1K Hz test tone at a distance of 1M. The deceptive part can be due to impedance of the speaker, and whether it is stated as 1W or 2.83V. If stated as 1W, impedance is irrelevant for comparing, however if stated as 2.83V and speaker is 4 ohm, that is 2W, and the 1W spec will be 3db lower.
Many smaller monitors do not do the lowest octaves much and are much easier to drive to high volume.
I only see this being possible if the speakers are being driven through a high pass filer, otherwise the small woofers will be overdriven into severe distortion.
Every 3db lower in speaker sensitivity will require double amplifier power for the same volume capability. So if you have 50w on a 92db speaker, then the following would be the required power for lower sensitivity speakers to have that same volume capability,
89db -- 100w
86db -- 200w
83db -- 400w
Again, since loud volume and dynamics at that loud volume are important, it just makes good sense to look at higher sensitivity speakers.