Best recordings to demonstrate soundstage?

I am interested in imaging and soundstage. I have picked up a pair of Thiel 3.6's and would like to test their imaging potential.

Box speakers are something of a problem for me because for some years I have listened to large planars, which throw up a huge soundstage. The Thiels have a much more constrained soundstage as compared to planars, yet they can seem wide and accurate and at times. With the right recordings they are absolutely amazing.

Hooverphonic and Morcheeba are 2 bands that I tend to use. Within their music there is so much going on. Sounds flying left and right, beautiful vocals centered, with layered vocals surrounding.

Can you help me increase my list? I love all kinds of music period. In your experience what is the best music and or tracks for highlighting soundstage?

Thank you,

Ron