I have a couple of those recordings, I'll have to listen to them with a metaphorical new set of ears.

My personal favourite test track is (surprise, surprise) the final movement of Mahler's 8th - the Tennstedt 86/87 version on EMI. It starts at a whisper, the choir rises in volume, providing a decent test of top-end, *everything* is going on towards the end, which leads up to the incredible thundering bass from The Westminster Cathedral organ (dubbed on after the fact, I've recently learned).

It's still my favourite 8th.

For sheer orchestral power and the potency of a truly great organ, Respighi's Pines are hard to beat. Small speakers need not apply.

One of the best played pianos you will ever hear. Underground trains are a bonus for big speakers.