It is awfully hard to find "full range" speakers that go down to
20Hz and the ones that do, are usually very expensive. I agree with
Eldartford, I would rather have limited range speakers than speakers that do
bass badly -- and, to my ears, there are many, many speakers that do bass
badly. If you are listening to rock music, you probably want some bass slam.
Getting that slam will be a function of two things; Speakers capable of that
bass and amplifiers that can control the speakers. Most likely, you're talking
about solid state amplifier and you'll need a fair amount of power. I would
call any speaker that can give a relatively flat response down to the mid
twenties, "full range."
As far as room response, you can go to various web-sites and feed the
dimensions of your room into a simulator and it will predict the frequency
response of your room. Having fed lots and lots of dimensions into these
simulators, it seems to me that most rooms have large peaks and valleys
between 35Hz and 100Hz.
This is why many acoustical consultants recommend using a sub-woofer with
a parametic equalizer -- to smooth out the bass response in the room.
