A belated thanks for your reply George !
I never have the problem of learning a whole sonata for the sake of one movement. I always seem to like all parts of a sonata equally. Or perhaps willing myself to do so
Amazing that you pick up the wall issue. Indeed the left side of my piano is very close (maybe 6 cm) to the wall.
However the recorder is placed parallel to the wall, facing me directly, so I am not sure how it would pick up a slap back - also the open lid would prevent that. Unless we're talking about the other (right) wall which is only 3m from the left (I have a smallish room as you see).
But, I'll play with the pre-delay as you suggest. Because sometimes the reverb plays tricks with sharp staccato notes (on the very rare occasions I actually manage to play those