It really depends on what genres of music you like.
I could recommend John Scott plays Liszt (Guild label), organ music played on the instrument of St Pauls. Its a good test of any system.
Swing when youre winning recorded by Robbie William is another well recorded album, but isnt to everyones taste.
Welcome to the pleasure dome by Frankie goes to Hollywood, especially the first two tracks, has some good testing moments.
Born Slippy by Underworld has an interesting interplay between the bass drum and bass guitar.
Maverick a Strike by Finley Quaye, especially Even after all, will test a systems ability to play deep. When the bass guitar drops an octave, it should be effortless and not overblown.
The list is endless and very much depends on what music you like listening to.
