What CDs do you use to evaluate gear, systems, etc

Here is what I use...

Rebecca Pidgeon's version of Spanish Harlem on Chesky album 'The Raven'.
Suzanne Vega's Jim's Diner on Solitude Standing.
Those are great solo voice.

My acid test is Henryk Gorecki's Symphony #3 for low level resolution at the beginning, great dynamic range and Dawn Upshaws spine decalcifying highs.