Can plugging headphones into a jack thats on damage or harm them?

[ph0ton.exe]

Ok so I just bought a new pair of audio Technica m50x's and thought I would plug them into my piano using the quarter inch jack that came with the headphones. I had my piano at a relatively low volume compared to how loud it can actually get. The piano was still on when I plugged in the jack. When I plugged it in, I heard that typical quik, sharp, staticy sound you hear when you basically plug a jack into basically anything (phones, computers, amps, etc) but in my ears it was noticably loud and sharp. Not loud enough that it hurt to hear it but loud and sharp enough to startle me. I turned off the piano with the headphones still in, fearing I had damaged the sound signature of the headphones. I unplugged them from the piano and then plugged them back in, piano still off. I lowered the volume and turned it on (headphones still in piano) and got that typical short buzzy sound you get when you turn an amp on only this time it wasn't as loud. I've been using them for about 2 1/2 hours now and haven't noticed anything wierd in terms of audio but, I wanted to know if it was, and is, posibble that you can damage or harm the headphones with that typical (almost normal) sharp sound like the one I heard.

 

[Robert Ban]

You can damage your sound system by using an for example 1000W amp on basic headphones and turning volume to max, that should burn the coil.
I used my headphones as speakers for short, nor they got damaged nor they got heated, soo im quite sure that they should be fine, you can connect them on phone or PC to test them out, as they are passive not active they rarley can get damaged.