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

All of us have favorite CDs which we use to evaluate components and systems. I would like to hear from you what CDs you use and how you use them to help you evaluate products, systems, etc.
I evaluate changes to my system with music I enjoy the most, after all it's those CDs I'm trying to heighten the musical experience of. Having an "Evaluation CD" I believe can lead you in the wrong direction, especially if that CD is just for that purpose.

I listen to mostly acoustic guitar, drums, piano and female vocals. Primarily Jazz, Flamenco, Bossa Nova, but most anything else. Artists like Steve Denny, Tom Maxwell, Robby Longley, Jacintha, Diana Krall, Tom Jobim to name a few.

A few years ago I told the guitarist Robby Longley I took his CDs with me when I was considering buying new equipment. He was quite flattered by that.
There are many threads on the Audiogon which will answer you question.

In my opinion one of the best way to evaluate a system/component is to use music which has plenty of acoustic instruments. I use it regularly and I am more than stisfied with what the results are vis a vis what I am looking for. You may do a search on your own to find many such threads, I quote just one example here:

Best acoustic -natural instruments CD's
Chris Isaak...Forever Blue...for soundstage depth
Massive Attack...for deep bass and transparency
Pink Floyd...for imaging...
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.