In context that he was a founder member played with is fine to mean he was still a member if wished you could clarify by saying he continued to play with them but it would be a bit long winded The second Melos bluelink is entirely optional the article isn t long enough to make it really necessary but repeat bluelinks from the intro paragraph into the main text are not uncommon and do sometimes help I can t decide if premiere for the Britten works should be singular or plural A footnote source for the appointments at Michigan would help as this is told on trust If there is more to add it would be nice to draw the sentences together a little more into two or three paragraphs But these are minutiae quite at your discretion all is well