I sometimes find Tim Buckley challenging too, especially the late works (such as "Look at the fool")..but Goodbye & Hello, Happy Sad and Blue Afternoon (strictly in order of "vocal innovation"

) are masterpieces (the others are great albums however)..I really love "Dream Letter" and "Cafe".
About Nick Drake, I too think Wings had some influence on the dreamful mood of Thoughts of Mary Jane. Besides this case, I find his voice totally different from Tim's, he was able to deeply touch you without any sort of emphasis or "intonation" in the singing.."Fruit Free" is an astounding example.
