difficult piano accompaniments for 4 part choir

[Alde]

Hello,
Can anyone suggest any difficult piano accompaniments for a 4 part choir?  These accompaniments could also be piano reductions but must be "standard choral repertoire".

Thanks

[leslieb547]

Not sure how 'difficult' you are seeking but here are 4 that I have done;
Stephen Foster - Jeannie with the light brown hair.
Mozart - Ave Verum.
Sibelius - Be still my soul (Finlandia).
John Rutter - For the beauty of the earth (and others).
Hope these are of some help.

[frederic chopin]

I have recently played Bach's St John Passion for my choir rehearsals - the piano reduction is indeed challenging.