On Mon, 17 Jan 2011 12:41:07 +0200
Moshe Werner <moshwe@gmail.com> wrote:

> Hi renato,
>
> only saw the question now, so sorry for the late reply.
> The input voltage of soundcards depends on the headroom of the AD of
> your soundcard. (e.g. Dynamic Range).
> Pro and semi-pro cards often have a line level of +4dBu (1.227V RMS,
> 3.472V Peak) plus a bit headroom.
> Hope this helps.
> Moshe
>

Yes, thanks. I might just try sticking in my USB function generator and
go up with voltage untill the sound card clips...

Also, I realized that putting a zener diode in parallel will just clip
the signal at the diode voltage, so it won't solve the problem.

A simple resistor in series with the piezo (of appropriate value)
should work, shouldn't it?

renato