I'll second Mickey Hart/Airto "Dafos". It was recorded in a theater in San Fran in the early 80's. I have it on CD released by Referance Recordings and can only imagine how good it must sound on 45 rpm LP.
To qoute the liner, "Consider that the sounds you hear on this album were recorded in a real concert space, not in a studio, were mixed on the spot to two tracks with no overdubbing, artificial reverb or equalization, and marvel at the engineering wizardry of Kieth Johnson."
This has become my reference when auditioning audio gear.