Kawai Synthesizers

I am new to MIDI (guitarist) and trying to set up a K1 for someone. I 
have the Kawai K1 with MIDI In and MIDI out connected, these run to 
the breakout box of my TerraTec DMX 6Fire 24/96 (with In to Out and 
Out to In). I am using CuBase 3.0.2.

When I press any key on the K1 there is a response within the mixer 
but I hear nothing. The audio is working (MusicMatch and other tools, 
including CuBase's opening music all play fine) but nothing from the 
keyboard. I note I am meant to add my device but cannot find out if 
the K1 is GM or GX. Any and all help would be gratefully received.