Can a power amp have too much power, risking damage to a speaker?

• It’s power that kills drivers
• High power amps are safe if you can fully control their output - this means know your volume knob’s "levels", and adopt patterns that prevent transient spikes - e.g. power on/off in the right sequence, mute when cueing a stylus, control LF feedback and woofer "flapping" if you have a turntable (through proper isolation) etc.
• Low power amps are safe if you keep them away from clipping conditions. At some point, power output may be low enough that even clipping doesn’t harm your tweeters - but I wouldn’t go looking to experiment on that.
• Tube amps are bandwidth limited at higher power levels, which causes their clipping wave to be *slightly* rounded compared to SS. But I can confirm, a typical tube amp’s hard-clipping still sounds like sh*t and can damage your tweeters - don’t rely on tube amps being much "safer" here.
• High efficiency speakers aren’t always correlated to higher or lower power handling. You can usually play louder safely with high efficiency. That’s why aficionados of loud sessions like me love them :)
• Tweeters typically have much lower power handling levels than woofers in the same speaker - up to an order of magnitude less. This is normally OK because like "pink noise", musical content carries much less energy above 4KHz (etc) than below - "equal energy per octave".
• When you force an amp into clipping, not only does it carry up to 2x the amount of continuous power versus unclipped (basic math - area under a sine curve versus a line), it also "rewrites" the signal to have a higher proportion of high frequency content. This is especially true for "peak" power. This is why it puts tweeters at risk - they’re not designed to take as much power as the woofers in the same speaker, so they’re sitting ducks under clipping conditions.
• Woofers are more at risk from poorly isolated turntable setups. Poor isolation and uncontrolled resonances can cause low frequency feedback. In the subsonic range, this is seen as woofer "flapping" - =-- besides power from the huge amplitude, it can cause woofers to hit their excursion limits and damage the voice coil. In the audible range 20 - 120Hz, LF feedback may be confused for ground hum at lower levels, and can even cause runaway feedback at higher levels. LF feedback can even get so bad it pushes your amp into clipping which then "suddenly" generates a HF spike (a very, very loud POP) that can kill your tweeters!

Mulveling, that is a terrific summary of the issue.

Remember this: "No amount of power will damage speakers if you use your ears and common sense to know when the recording comes into its own at a particular power level. I used a 400-watt power amp with my Electrostatic Quad speakers with absolutely no issues.

@phillyb

From the number of damaged speakers we get in for service, I dont think your idea works in practice. And Im lost when you say "know when a recording comes into its own at a particualr power level". I assume you mean that you should be able to hear when it begins to distort? Gosh I wish you were right becasue if this were true I would never get a blown speaker/driver in for service!

I’m also not clear on this idea that Recordings have a favored or preferred power level (assume you mean playback SPL). Playback systems systems do have a maximum power level, but Im not sure they have a preferred or even minimum playback SPL we could all agree on.  QUADS were notorius for having a very limited max power level and limited dynamic range so perhaps your hearing is oriented around this?  (Billy Woodman from ATC loved loved loved quads for their extreme definition).

Recording systems also have "preferred" input gain settings as well but even this is up for debate in practice. There is a well known story of the Beatles arguing with the Abbey Road Engineers that a distorted input signal (exceeding the preferred input gain of the system) was NOT a mistake.

Provided a high power amp source with multiple times the output of a quality speaker’s power handling capacity, it would usually take quite the beating for longer durations for the speaker to actually fail thermally and/or mechanically. Before that happens there’d be sonic implications going from dulled dynamics to outright strain and severe mechanical distortion, and if in the meantime one doesn’t identify these signals as warning signs, well, then I’d seriously question that individual’s ability to assess sound in a fairly skilled manner. Misuse of one thing (incl. what can lead to  all sorts of accidents, some of which are already mentioned in this thread), but unless we’re partying all night with our brains shot without any care in the world for the equipment used (not to mention our ears), most of us around here under more controlled and sober conditions should be able to properly assess when it’s time to ease off on the volume control and call it a day.

Really, it’s not that complicated. How many amps are there in the kW’s range? Buy whatever you like that fits your sonic and SPL needs, and if it means going with an amp that has more power than the speakers rated power handling, don’t worry. On the contrary, I’d worry less, because all things being more or less equal and provided again some common sense use, that amp should perform more effortlessly and with lower distortion at a given, higher SPL.