I should have come into this thread earlier. I have a nomination that (probably) few of you have even heard, but an absolute piece of art musically and recording wise.
The release was in 1976, by bassist Charlie Haden, who recorded eight duets with musicians whom he admired titled "Closeness Duets," on A&M Horizon.
The recordings feature Charlie Haden with Keith Jarrett, Ornette Coleman, Alice Coltrane and Paul Motian. The cut titled "OC" is stunning, and has an unbelievable piano and string bass portion that stuns me every time I listen to it. My copy is on LP, but I believe it is available on CD as well. The quality of the CD is an unknown to me.