As a broad generalization and within reasonable perspective, it is not possible to have too much power, but it is VERY VERY VERY much possible to have not enough brains.
I know of a guy who uses 1500w/ch to his two front speakers, and he tests common consumer speakers all the time (Z Reviews - YouTube) without any problem. How and why? Because he is smart enough to understand the capabilities of is equipment and the limits of his speakers, and he uses both wisely.
To summarize -
It is never over-powered or under-powered amps that blow speakers; it is always the guy running the Volume Control. Don't be that guy!
And yes, under-powered amp can blow speakers.
In my entire considerably long life, including some heavy partying years, I have never blown a speaker. Though a friend of mind did when he turned it up above the level that I specifically told him NOT to turn it above. Blew a Tweeter.
Certainly there is a danger to having massively powerful amps, but understanding and moderating that danger can also be accomplished.
Also, consider, if you have a 200w/ch amp, how often are you going to be running it full bore wide open? Not that often. Likely the music/movie might very briefly jump up to the peak power, but very very briefly, especially with 200w/ch. TIME MATTERS, what a speaker can sustain for a fraction of a second, it can NOT sustain for several seconds.
Most of the time you are cruising along at between a fraction of a watt and 4 watts. Yes, peaks are jumping higher, but the average power is generally pretty low even if the sound is generally loud (reasonably loud).
Also, as many of you know the expansion of Power is not linear. It ramps up very very very very quickly on the high side of the Volume Dial.
The B&W 607 is rate at a modest 84db at 1 watt, so here is how power ramps up with increased volume -
84db = 1w
87db = 2w
90db = 4w
93db = 8w
96db = 16w
99db = 32w
That's fine as 99db is pretty darn loud. But watch how the power start ramping up very very quick from this point onward.
102db = 64w
105db = 128w
108db = 256w
Though if you are up in these sound level ranges, you are pushing your small speakers pretty hard. Likely not only are you pushing them beyond there electrical limits, but you are very likely pushing them beyond their Mechanical Limits. Don't be that guy!
Now in the example I gave of someone having 1500w/ch Amp, that is extreme in the absurd, though he seems to make it work (Crown XLS amps in Bridge Mono).
For most consumers, the sweet spot seems to be in the 80w/ch to 120w/ch range (more or less). Though amps up to 200w/ch are not that uncommon. Over that amount (roughly) you are getting into excess power, and to have that excess power, you need to wield if VERY WISELY. This is especially true in consumer grade equipment.
Just a few general thoughts.
Steve/bluewizard
I know zeos, we where today on the same twitch stream (none of us where streaming at the time)
The amp is 2400 watt, the reason he got them was he had the behringer A500 bridged, 500 watt pr channel in 8 ohm, since he somtimes play loud, the amps got hot, there was distortion without the speakers being used to it's maximum (Ohm walsh 2000).
Distortion won't hurt or else a distorted guitar will damage a speaker in no time
Clean unclipped power won't hurt speakers, unless your try to play so loud your speakers can't move any more and you go from 12 o'clock to 3 o'clock boom damaged speakers, even when your amp don't distort (lets say zeos power, 2 bridged crown xls 2502, 2400 watt pr channel)
Dynamic music or bass (i could link to a video if i wanted to, i don't) requires alot more to sound loud (bass heavy music) than let's say classic music like beethowen (not the chuck berry song) or mozart.
Zeos wanted more power so theres no clipping,distortion, EVER and so he doesn't have to use the amp to it's limit where it's get's super hot, in my experince most consumer amps do change there sound signature and distort a little when pushed to it's limit, thats why you don't want to play close to it's limit and also have to take care when having 2400 watt pr channel, since theres no indication of the sound changing (reaching it's power limit), other than being louder and no distortion to tell you, your reached you amps limit, turn the volume down.
The db sensitvity is not that simple
84db = 1w
87db = 2w
90db = 4w
93db = 8w
96db = 16w
99db = 32w
Wharfedale diamond 225 rated at 87 db, max power i don't know, recommended amplifier power 25-120 watt, peak spl rated at 96 db, granted 96 db is loud but not when you realise it's less than 10 watt and the speakers can handle alot more than 10 watt
Diamond 225 – WHARFEDALE
So fare so good, im not gonna use 2x200 watt in 8 ohm unless like in the harbeth video i could link to, a speaker needs alot more than 50-100 watt of unclipped watt to play some dynamic bass heavy music at high level,spl.
I never try to play louder than my speakers can handle, if i hear distortion that's not related to the recording im listening to, it's because im reaching the amps limit (i have had alot of low powered amps).
My speakers are rated at 84 db (mabye lower, many speaker have lower sensitivity than rated)compare them to 90 db speaker with a 50 watt amp many wouldn't need more but theres also many young or old that say this kind of power, 2x50 watt and 90db isn't party level, if i had 2x200 watt i would have the samme power.
like a very power full car with alot of horsepower and torque, you don't need to push the engine to it's limit to have enough power, make the car fast, same with a more power full amp, you don't need to use all of it's power to have enough and you get the advantage of low distortion (no clipping,distortion ever) and control without playing louder than i can atm with my nad c352
Im just not going zeos crazy, i don't want and need 2x1000 watt in 8 ohm, i even don't want and need 2x500 watt, how ever 2x250 in 8 ohm, now we are getting there, 2x150-200 watt with more to the 200 watt pr channel than 150 watt is what i would go for, not alot more
I do have a lillte experience with a pa amp, 2x300watt at 1khz in 8 ohm and 88db sensitive Mission QX2, that was a very power full combo, it was just to much, the bass,bottom was to full bodied and i could play impressively loud, so fun i did play to loud to often.