B&W 604 s3 or B&W 683 s1

[Singingtheblues]

Hi can someone please give me some advice I currently have a pair of B&W 683 s1 as main speakers with the Lcr60 centre, 603 s3's at the back and middle 602 s3. I have the chance to buy a pair of 604 s3's. There's a lot of bass from the 683 s1"s but not much treble.The question is to stick with these or would the 604 s3's be better.