Maybe it would be a good idea to try different mouthpieces, a different ligature won't really affect the sound. (If it does then it most likeey means your current ligature or mouthpiece is damaged or warped)Ticho said:
An S80 shouldn't really be over bright - you should be able to get a variety of tone colour, so I would suggest working on embouchure. I think the best ligature for a Selmer mouthpiece is a Selmer ligature, they are very good.