Kal,
Thanks for the reply. I forgot the input is "line-level".
I will investigate possibly bridging the two channels.
Thanks.
You might blow the amp with this idea. Your speaker must have double the
specified minimum impedance, so if the amp is for 4 ohm speakers, in bridged
mode it can deliver double the power only to 8 ohm speakers. If you connect
a 4 ohm speaker to it, it will get in current limit situation and the output
power will also not be bigger than with a single channel. If you overload
the amp this way, it might get hot and this will reduce MTBF (Mean Time
Before Failure).
You can get a stereo line transformer from radio shag. operate both inputs
in parallel and just inverse the second output. Then you do not need to
fiddle with an additional power supply and some electronic inverter, because
the output of the amp is usually in phase with the input and you cannot use
it to derive an inverted signal. The loudspeaker is then connected to the
two red terminals.