[sdiy] Protective Earth on PC soundcard GND?

[JH.]

Hi,

still considering various PC recording options, here's a stupid question:

Is the GND of typical PCI soundcards floating, or is it connected to
protective earth
inside the PC? (speaking about European mains voltage, German in particular)

Background: I wonder if it's worth to invest in a balanced in/out card,
because
my mixer has unbalanced (RCA, -10dBm) inputs and outputs for the tape
machine
(wich will be used to interface a 8in/8out soundcard).

I'm aware that I could take advantage of balanced TRS inputs on the PC even
then,
connecting the hot RCA pin to the TRS tip, and the RCA-GND to the TRS Ring,
leaving the TRS sleeve unused (or connected via resistor), thus avoiding a
ground
loop.
But the other side, PC balanced TRS outputs to unbalanced RCA inputs on the
mixer,
would only work if (*if* !) these TRS outputs would really be "floating
balanced"
(as with a transformer, or with a special cross-coupled opamp output). But
I suspect "balanced output" all too often means just complementary signals
which are
both referenced to GND, in which case a tip/ring to RCA connection will
be fatal (or at lest not break a ground loop).

OTOH, if the soundcard has no connection between GND and PE, all would be
fine.

That's why I am asking.

(I still have this unexpensive M-Audio Delta 1010LT in mind, but I'm also
asking
if there is a general convention of connecting, or not connecting GND and PE
in a PC ausio system.)

JH.