Use this song if you are doing an A/B with Preamps

Actually, in this experiment the limiting factor is generally the amplifier not the preamp, in my experience.

Streamed with Tidal Masters. It may not be up to Audiophile Standards, but - a lot of songs I like are not as well, and it's OK. For me, I want the system to do a good job rendering less than perfect recordings. The fact is, Diana Krall sounds good on All systems.
After settling in with the same amp for the past year, I was surprised how differently the song sounded by changing only the Preamp. It was less noticeable on Diana Krall and Dire Straights material. 

I disagree. Diana Krall does not sound good on any system.

Hire this man!