Forgive me if I am missing the point here, but - unless you are a professional reviewer or demonstrate kit to the public - the best 'test CD compilation' is going to be a mixture of music that you and your family enjoy rather than what we like.
I assume you need something to take around hifi shops to test new gear so your own music is best.
I would (did) turn up at my dealer with CDs of the Tallis Scholars (Palestrina and Hildegaard Von Bingen), Handel's Messiah (John Eliot Gardiner & Monteverdi choir etc), The Seekers, XTC (English Settlement), Spike Lee (Do It Acapella), John Coltrane, Stranglers, 1970s compilation with lots of really naff Pop stuff that I still love and half a dozen other Rock/Pop/Jazz/Classical CDs.
If I was to recommend one stand-out track to hoof up the volume with, then Steeleye Span's 'Fighting For Strangers' (from 'Spanning the Years') is awesome and will seperate 'the men from the boys' in so many ways! (Forget Steeleye Span's normal wimpy folk pop, this one track is a hard edged and bitter war protest song with a collossal sound and massive soundstage and impact.)
For a small idea of what it sounds like, plug some headphones into your PC/Laptop and listen here... http://www.last.fm/music/Steeleye+Span/_/Fighting+For+Strangers
... obviously the CD version will sound better.