Maybe you should check the bass settings in the sound menu. Perhaps all the bass of the speakers is redirected to the sub. This may give a very thin sound.

Did you (or your dealer) set up different Speaker Groups with your specific speakers?

Otherweise you will only get sound from the default Sound Group (probably called ‘tv’), which is the internal speakers L, C, R.

MM

Your set-up is wrong... I assure you.  The sound from the Avant 55 is brilliant!

I've had a few, and the sound is very 'tweakable' - and as standard it seems to give little credence to any speakers connected to it from experience.

Have a play in the sound set up menu, make sure the inbuilt centre speakers are split to left and right stereo, and 'turn up' your connected speakers.

Lee

In my experience the Avant plays more through its own speakers in comparison to the Beovision 7. The Beovision 7 had a more balanced multichannel setup out of the box, even though this is only my opinion. So just turn down the avant or turn up the attached speakers. 

Have turned down the centre but little difference , when playing a CD i would expect a stereo sound but again seams mostly from the tv and very faint from the attached speakers .

As Michael wrote,

please post some pics of your settings and give details about the speaker setup - otherweise it will be hard to give you any further advice.

There definitely is something wrong there!

My BV Avant plus external speakers performs well - in fact I never had a better setup.

MM

a2bur wrote:

Have turned down the centre but little difference , when playing a CD i would expect a stereo sound but again seams mostly from the tv and very faint from the attached speakers .

With stereo sources/music, my speaker group is 4.0, so the Avant does not play at all. I highly recommend this for music.