Nice spot! Would love to see what’s up with the discrepancy. That’s most certainly not peak power in my experience though because if I remove my volume limiter and bias the EQ towards bass I can definitely get more oompf out of this thing than even 100W dedicated subwoofers which I know were spec’d correctly. I wouldn’t jump to the conclusion that the specs are entirely BS yet though but they could definitely be stretching the truth; because we do know that we can get this kind of power out of chip amps (running them parallel and what not) into a single woofer. Who knows, maybe the 2x200W claim for the woofers is peak for a few ns/ms lol which is in no way sustainable for however/whatever methodology they use to come up with that 100W figure on the label. Shrugs. Anyone with more knowledge able to chime in here?
The same way my Devialet Mania says it does ((2x38)+(4x25)) = 176W; Onboard power storage.
In the case of the Devialet, though, they have capacitors and a fairly sizeable battery. They could pretend that the battery is capable of producing 176W when necessary, but i doubt that can actually be done. The Charging cable maxes out somewhere around 35W from my testing, and is rated for only 30 watts. The battery in there is 11 volts, so that would be 16 amps peak draw from a small lithium ion... Not likely, but i guess technically possible.
The 100W in the B&O is likely pretty close to correct, but might be off by a few watts up or down. No way it's feeding even one of those woofer amps, let alone the two plus others. I bet it's not much more than 110W or it might be considered some sort of safety issue to say 100W on the label.
And the B&O ain't got no battery.
So we're left with capacitors. Caps don't hold much power but they can hand all of it out almost instantly i f required.
The amps i've played with typically have a power supply refilling some bulk caps, and the amplifier drawing from those caps. If you draw more continuous power than the power supply can replenish, the voltage in the caps drops and the total output of the amps ends up being whatever the power supply can give minus the efficiency losses (and usually adding some terrible distortion).
But if you have brief peaks (maybe a cymbal crash or the attack on a particularly loud note) followed by a few moments of lower power draw (maybe the sustain on a piano note or just whatever thing is happening that isn't incredibly loud), then you don't drain the caps too much.
Decently mastered music often has a few notes that go right near clipping for a few wave cycles, or even a half a wave cycle, followed by time at a much lower power level.
When the peaks are short like that, the capacitors don't discharge too much and your average power stays relatively low.
So at full volume on the B&O (well, probably. It's complicated), those peaks might hit 850 Watts. And theoretically, that should be okay so long as the average power over maybe a half a second or a second stays below 100W.
If your volume is a little lower, power requirements drops substantially. Most people will still think that 850 Watts is still doing them some kind of good below max volume, but it isn't. (again, probably. It's complicated.)
On the other hand, that doesn't actually meet the legal requirements to advertise amplifier power in the US, as i understand it. (i'd love for someone to chime in if i'm wrong).
But then, on the third hand (you've got one, right?), it doesn't really matter what the amp power is like because speaker efficiency plays a part as well. Plus there's likely some cool DSP stuff going on. (Well, in the Mania. Who knows what B&O is doing with that crazy frequency response...)
That DSP stuff might, depending on the implementation, lower the peak possible power out of an amp.
To sum up: it's all a terrible lie, and plenty of people buying a Bang & Olufson speaker generally won't look into or maybe even understand it. It looks pretty and the bass probably hits harder than the tiny speaker in your phone or a cheap soundbar. The bass should kick the ass of any bookshelves a B&O owner is likely to buy.
So who cares if the label is lying to the customer?
Either way, i'd avoid playing dubstep near max volume. If you're lucky, it'll either cause ridiculous distortion, or trigger some power protection circuit. If you're unlucky, it could let some magic smoke out.