Dear Lew, No reaction from you so I will answer your logical
question. Your assumption is:
''No x Fx and Gx''.
My assumption is:
''some x Fx and Gx''.
My assumption is true if there is just one member (of set x) who
has heard both (F) Klyne 7 PX and (G) Van den Hul's Grail.
Your assumption is false if there is just one member who has heard
both phono-pres.
Because nobody answered my question you are probaly right.