Most Influential Chamber Works

[eschiss1]

To put a slight but only slight tweak on the list-making (e.g. the best symphonies of the last 50 years threads), I do think I'd like to ask for peoples' opinion - with reasons, and short lists but not of strict a priori specified lengths - of what have been the most influential chamber works published or first performed in the last 75 years.
(That's date published or first performed; works composed but not yet published or performed are usually, with some exceptions, not very influential beyond a very small group if that. Of course there have been some important exceptions!

The arbitrary 75-year limit does leave out some fairly influential works, like Webern's saxophone quartet opus 22 (first published in 1932, 79 years ago), etc. Bartók's 5th quartet does fall within, as it was published in 1936 (whether it's one of the most influential chamber works of the period 1934-2011 would need to be argued though... hrm- maybe the 6th quartet, especially structurally?)
Anyhow. Will try to draw up a list during my upcoming break I think. Over to you if the topic at all interests.

[BFerrell]

The Rochberg Concord Quartets had a tremendous influence in halting the serial cancer growing throughout the "White Tower" intellectual world. It helped open up the floodgates since then. So, I would call them extremely influential.