Disable internal peacker of 712/80

[Timo Springmann <timo@OrangeOrb.de>]

Hi there!

I wonder if there is a way to mute (or disable) the internal speaker of
my 712/80 box? I've connect the HP to my amplifier and it sound somehow weird
if the sound comes from the HP _and_ the amp. I played around with aumix
but I thinks you can only control the loudness of both (Amp-speaker and
HP-internal-speaker) at the same time... 

so long,
Timo