Rubinstein's recordings of Chopin's Nocturnes are some of my favorite piano recordings of all time. The ones I have though are from the mid 60s. I tried recording my piano at my home a long time ago hoping to get that sound - NOT... His touch was so amazing... and the sound so beautiful. Check this one out:
http://www.youtube.com/watch?v=QAcAWWU_0mE - that's the one I tried to record myself doing way back when. His sounded much better - hehe.
According to the liner notes in my Rubinstein Nocturnes collection, the original recording was done to 3-track 30-i.p.s. tape. Playback was through a solid state 3-track tape machine, but they left out the center channel and only used 2 tracks on the disc. The booklet says "an equalization curve was devised to flatten the bass dip, mid-range and high-end peaks of the microphones used for these recordings, thus giving the sound of a flat microphone response." There is no information though about the specific microphones that were used, or how/where they were positioned, etc.
My set is a 2 disc set - recorded at RCA Italiana Studios, Rome, August 30 and 31, September 1 and 2, 1965. Recording Engineer: Sergio Marcotulli.