Oh right, thanks Bill, though I hope not!
From what i've read, I thought the head unit is the same regardless of base/hifi/HK, (i.e. no amp, 'analog' hifi amp or HK amp using optical MOST) the Nav option is what changes, could be completely wrong here though?!
It wouldn't be the end of the world, as I can change the amp EQ/DSP, but i'd rather try and start with a flat output than polishing a turd, so to speak!
The main thing is that the base stereo EQ changes with respect to volume setting, which isn't ideal.
Thanks, James