[PD] (OT) safely connect piezo transducer to soundcard as microphone

[Matteo Sisti Sette]

Hi,

This is OT but I'm sure many of you have used piezo microphones sometimes.

I've often connected a piezo transducer to the microphone input of my 
computer (and other computers) by simply soldering the two wires to the 
T and S of a minijack plug, and it works just fine and my soundcard 
hasn't suffered any damage (apparently at least).

However, I am concerned that a strong sound input (e.g. hitting the 
piezo transducer with with fair strength) may actually generate a 
voltage peak (thought only for a short time) capable of damaging the 
soundcard, couldn't it?

Also, a friend of mine did the same with his Macbook and his headphones 
output has stopped working (may be just a coincidence though).

Is there an easy way to make it safer? I seem to remember I had read 
somewhere (can't find it) about connecting a 1MOhm resistor in 
parallel... woudl that do the trick?

thanks
m.