Philips 9607: Can you disable the Sub?

I am finding the built in sub a little boomy.

Whilst I love base, I get all the bass I need (When watching movies) from my REL.

But when I watch 'normal' TV, ie Eastenders, I just use the TVs speakers in Stereo... But the Bass is a litle too overpowering.

For example, in Eastenders, there is often music in the background.. On the Philips, the bass line/thump of this music can be clearly heard.

I have tried turning down the bass, and whilst this helps, it makes the normal (i.e not sub-base) disappear too making the sound very flat.

I would like to leave the bass up a bit, but disable the sub-woofer.. Can this be done.. Perhaps in the service menus??