I am not sure what that Electrovoice 30" speaker would handle but looking at another website with *.pdf files for old speakers and such stuff, it usually was something like 250 watts with peaks to 1000 watts, which still for the time is not all that much. But compare to looking up JBL and see that now professional speakers go around 600 watts and well the entire cabinet can handle up to 3200 watts peak. I just sit here and be amazed, because my JBL are really kind of old with paper cones and handle 150 watts with 600 watts peak so just one side handles about 265 watts with peaks accordingly. I do not know, since I use to use them but built the cabinets and they need kind of repair work since I put the duct for the woofer in the back for more surround type sound. And anyway, I guarantee that you would not want them that loud for your TV movies in the place that you live. I have an old NAD amp that puts out 40 watts but peaks at 260 watts and after awhile that is even loud, but was something new when surround sound movies came out on tapes. But anymore, even DVD movies only have hi-fi sound instead of also the mono type sound one can set with a VHS recorder which is good enough for me, since with movies they include all of the sound with everything going on including explosions and whatever. After awhile even Star Wars gets old with surround sound and putting up with all that sound.
The headphones (which I just bought new ones - Bose - which don't seem as good as my old ones that rattle now on one side) typically only handle 100 milliwatts of power so at what they claim is something like 10-40000Hz frequency response is only the total of what they will handle, but typically the real response is good enough, just like speakers that claim they handle 20Hz to 20000Hz, but when looking at the fine print it is typically + or - 10dB or more, and even in the good range usually + or - 3dB or even around 6dB.
Everything in sound has sound characteristics even microphones some of which like ribbon mics sound better usually take less over total power (blow out easier) but good enough to be used for like symphony recordings or orchestra recordings then on to dynamic mics which handle more power but usually sound different or not at good as ribbon microphones. It all costs money, and a lot of money can be spent on that stuff.
Usually the speaker will be the weak link of a sound system and that is why they still try and create different type of speakers like they do, but in the end, the efficiency is still weak and it is a piston and mechanical movement device, except when they use like a horn speaker with its radially designed curve whatever you call it, exponential curve I guess and then the throat of the diaphram they use is way smaller and the horn makes the loudness for the sound but then it sounds like a horn also which sounds like a horn which is more efficient but still sounds like a horn, which a lot of people do not like. It just ends up being cheaper I guess. I sure one can look up sound arrays in various buildings they have put in because they end up taking measurments and everything of the room characteristics that also add to the sound in the end. I remember one, maybe Carnegie Hall perhaps which is on the Internet or something like that and the entire type of the stage area all way across was nothing but array after array of speaker banks in the building which is I guess around at least 50 feet across, but with stacks of speakers way up high hanging there and directed to cover the entire room.
It gets quite involved just to put up speakers in a football or baseball stadium and run 70 volt lines with a room of amplifiers usually put in and the 70 volt lines ran out throughtout the stadium. Just can not run speaker wire with a setup like that. And then they usually are using horn speakers but then it is not a full-range speaker system but more a PA system still using a lot of amplifier power though.
