I have been happy with several of the performances and quality of the recordings from the following:
www.channelclassics.com. Try Art of Fugue by the New Centruy Saxophone Quartet (very interesting), any of Rachel Podger's Violin Concertos.
Hi-res downloads and interesting music from http://www.2L.no/
Hi-res downloads and broad catalogue from http://www.linnrecords.com/.
Sadly, "avant-garde" jazz seems to be not so avant garde from a current recording and distribution perspective.