Recommendations for impressionistic etc. String quartets

[konstantinos]

Hello.
Since I love the orchestral sound more, I'm not so much aquainted with string quartets.
So, I'd appreciate it if you could recommend any good and essential ones (except the Ravel and the Debussy ones) in the impressionistic style or with more extended harmony (but not atonal).
Music that its score is in the imslp database would be preferrable!

[jossuk]

"Impressionistic" can be a rather loose term, as a cursory scanning of web links will quickly reveal. Since it sounds as though you are first concerned with hearing rather than playing the music, I would recommend listening to the quartets of Janacek (IMSLP files), Delius (IMSLP score), John Alden Carpenter (IMSLP score, but non-PD in US and EU), Respighi (IMSLP parts only for st. qt. #3), and Szymanowski (IMSLP score). Also Bartok (variable IMSLP items, PD and non-PD), Prokofiev (IMSLP score and parts for st. qt. #1 - non-PD in US and EU) and Shostakovich (no PD items that I see).