A full range speaker?

I’ve always understood full range to be 20hz - 20khz very few passives unless they are pretty large can do full range. I don't know of any that will do full range with an FR that looks decent without PEQ preferably DSP. 

I think the the 20's are the domain of plate amps. Some manufacturers are now including them in their full range speakers to drive the big woofers.

Something I have seen that seems like a good idea is a built in high pass filter on a preamp. This is something that should be a given, as all that comes from passing tones lower than your speakers can reproduce is distortion, and wasted power. What's the point of your amp receiving that info and wasting energy trying to reproduce it if your speaker can’t reproduce it? I think the Parasound Halo has that, although some people may frown on that as being marginally worthy of being lumped in with audiophile equipment. But I’m more like Steve Gutenberg and Herb Richert in my inclusiveness of trying to find a decent system for people that can only afford say a grand on their system.

But I digress…

Full range is a quadratic equation. If your mids and tweets are 100 watts, your subs have to have 800 watts and four times the surface area of the mid’s. 
And this is an area where class D amps don’t cut it, in my experience; so double that to 1600 watts RMS for 20- 80 hz.

This may be useful for some - here's a Sound on Sound page with a link to a frequency chart in the top right corner. Fundamental notes are within the range of 16Hz to 9kHz, with harmonics going much further up in frequency. If you don't listen to a lot of pipe organ music then a lower bound of 30Hz will include all the fundamentals e.g. if you mostly listen to rock music low B on a 5/6 string bass is 30Hz and you'll hear everything a 22" bass drum has to offer from around 55Hz up.
Providing you have a loudspeaker that will play low enough the room will dominate the frequency response below the low 100s of Hertz. As loudspeaker placement is key to getting the best low frequency response it can be beneficial to allow one or more sub woofers to take on this duty. In a large, acoustically controlled space this is not so much of a problem and it matters less if the low frequencies are coming from the same cabinet as the bass, mid and high.
The high frequency response is bounded by our ability to hear and 20kHz is well outside of this range assuming most of us are beyond our teenage years. There may well be recorded content above this arbitrary limit but I won't be able to hear it and so I don't miss it if it's not reproduced.
So for me 30Hz-20kHz is fine and I'm not sure I'd notice too much if it was a smaller range than that. I build equipment (not loudspeakers) to exceed 20Hz to 20kHz because that is the defacto standard.