I have no idea about classical music but dd (nearly 7) likes listening to it (for relaxing and imaginatory purposes)
Atm she likes listening/watching 'The Draughtsman's Contract' on Youtube, also Classic FM (but too many adverts Mummy). She also liked the Schubert and Bruchner (sp?) cds which we found when we were on holiday last year.
She seems to like mellow cello or violin based music so would be grateful for any suggstions.