I think I can add to this observation, because in the mid-1970's, (1974?) the IAO Congress assembled in Chester, shortly after the release of the Reubke recording mentioned. I think oit would be fair to suggest that this one work established Roger Fisher as one of the truly great performers of the day, because the depth went far beyond the notes.
I had been building myself up to the moment that Roger Fisher played to us, and to discover that the programme would include the Reubke Sonata on the 94th Psalm had me in near palpitations of excitement.
I do not rememebr anything of the recital other than the Reubke, but when started there was total silence in the audience; so sinister and brooding were the first few bars, we were rivetted to our seats. As Roger unleashed the anger and passion of that sonata, (on a truly superb and hugely powerful instrument), I think I can speak for everyone there, when I say that it was absolutely terrifying and electrifying in equal measure.
I cannot recall another recital when, at the end, there was a substantial pause before anyone dared to applaude: it was that shattering an experience. Of course, when we did applaude, it went on for quite some time, but almost tempted to crawl out the cathedral on my knees like a devoted pilgrim, I was soon bumping into people who had been stunned into silence, or who just spoke words, such as "Wow," "My God", "Incredible" and "Devastating".
I think it would be fair to suggest that it is one of only three performances which have absolutely slayed me; the other two being by Dr Francis Jackson and the late Fernando Germani.
It just doesn't get any better than this, and for my money, it is the greatest performance of this extraordinary sonata ever.