The only mention of 119dB that I could find was in relation to their sensitivity, which the website claims is 119dB/V and the quick guide claims is 124dB/V (both at 1kHz, lol).
Where does it say that 119dB is the maximum level?
Hmm. I was looking everywhere, and it was the only value I found anywhere. I didn't bookmark it and was on like 50 sites, so unforunately...
It does seem likely that I or they misattributed the 119dB
The IE 200s are apparently 18 ohms, so 1V into 18 ohms is 56mW. With 56mW it makes 119dB, and 1mW: 101dB. 18dB is about 64x power, and since 56 is pretty close to 64, it looks like 101dB/mW is the correct efficiency rating.
Yeah, the dB/V is just one of the two standard units of measure for headphone efficiency - it has no bearing on maximum level. It could probably be given for a headphone that's not actually able to generate that SPL - extrapolated from a lesser voltage.
I don't want to cook the tiny 7mm things... They do seem extremely capable though, especially coming from my last IEMs (Salnotes Zero). The IE 200s bass has less distortion even though its driver membrane has less than half the surface area of the Zero's - and the midrange just seems... more realistic. The IE 200 can be a lot smaller (and it is - literally ~half the size) of the Zero with the same frequency extensions etc. (approximately...), and since the driver apparently can move at least more than double the distance of the 10mm in the Salnotes Zero before distorting, it takes advantage of having the smaller, lighter, more rigid, less resonant case. Anyway...
I really really like knowing the power ratings of things... I'm very happy to know that my HD 650s are capable of 500mW average power and put out ~100dB per mW over most of the audible spectrum. I like knowing that my ears will be very uncomfortable before any damage is done to the drivers, unless the damage is from a freak accident - something like a tonne of LF energy immediately. Since I generally try to take care of my hearing, I know that there's nothing extra I have to do to ensure my headphones are looked after as well. Random fact: HD 650 xmax is about 2.5mm peak to peak, pretty impressive IMO {{I had the ear pad and flat foam piece off, and you can see the center half of the driver right there, so I though: why not?}}
I've even tried looking for the power rating of their other IEMs with no luck! Maybe Sennheiser believes that people don't need the power ratings because the IEMs can go to uncomfortable levels before being damaged themselves...
I did a bass test of the IE 200s, the same thing I did with my Salnotes Zeros: Put various low frequencies to them and increased the level by 0.1dB until xmech is reached (audibly when the voice coil former part of the membrane reaches the magnet, it's a very faint clicking). When doing the Salnotes Zero, I actually began smelling the drivers in the 50Hz range. Granted, I'd already been testing 20, 30, 42, 47Hz, each for maybe 20-30 seconds up to xmech, but still, it's pretty extreme to be literally smelling up the place (Zeros don't smell during normal use. They sound decent if you equalize - they're good value for $20)
Maybe you see now why I'm slightly anxious to know the power rating