I can't think of one single song that I would use to test speakers, going to high end hi fi shops is a hobby of mine when I am on the road and I have 3 discs I use, just burnt off the pc discs... I don't listen to all sacd quality music so I wouldn't use them to test something I am considering purchasing since it could be a let down when I get home and throw my ipad on, lol...
If I had to pick one short list of songs Cafe blue is on the list and it's a good song for test demoing, A few others I like to use are...
Fairfield Fours "these bones" the deep vocals {Isaac Freeman} in this song show how a speaker reacts reproducing to voice down in the basement, I am not sure how deep Isaac goes but I can tell you I have a system crossed rite under 80 and hes comes through the subs... This song is going to show you much in the way of instrumentals mind you but there are some decent ranges and smooth transitions so you can get a good idea how the speakers perform in the low to mid vocal areas..
Next would be
https://www.youtube.com/watch?v=rYEDA3JcQqw "rolling in the deep" If I had to choose a single song, believe it or not this song would be in my top 3, its fast, slow, medium speed all over the place, her voice is special in the way its female but can dig a little here and there, while her back up is towards the top, the bass in this song {while your pc probably wont pick it up} shakes my house, I have seen many show room "guys" say "wow this song has some bass notes in it" they are hidden, lol but on the right system they are there... plus snapping and clapping is very revealing, some speakers just don't do it well...
Clapping brings us to Stealers wheel "stuck in the middle with you"
https://www.youtube.com/watch?v=DohRa9lsx0Q with some speakers the clapping in this song sounds like drums, lol and with decent speakers you will get it all, you will hear them pulling the beer bottle over the strings, all the claps will be effortlessly noticed as being claps, ect... A lot of foot taps, claps, and other hidden sounds in this song, with good equipment it will be like hearing it for the first time, this is another one the showroom guys always take a note to put on their list, actually I have had numerous stores, copy the cd, lol...
And the last one I would put on my "must listen to know" list would be Roger Waters "What god wants", thiis on his album for the early 90's not pink floyd, sit in a decent speaker {2 or 3 way design} in the sweet spot and close your eyes, I know where the spots are so can sue to them pretty fast, but these 3 songs were recorded in Q-sound which was a 3d way of mixing used and this will reveal to you a speakers stage, if the speakers are done right, you will notice a center vocal localiaztion with almost every song you listen to, unless they mixed it to not have that effect, but with these Q sound songs, you will notice the sounds come from far beyond the speakers position, at some points they are behind you, with my system you swear there is a rear speaker... Pink floyds Pulse was also done with this technology another song on my list...
The rest of my songs are all stuff I am super familiar with, if you listen to a song that you hardly or never hear, than how can you compare them speakers to everything you heard in the past... You wont remember a certain sound but you will remember something new or something missing that you look for... Listening to music can be an art in itself... Don't get too hung up on having the "best" source material, sure have a nicely recorded cd, but keep in mind not everything you listen to is going to be sacd quality, and honestly there are only a few sources that make a difference to our ears, we just can not hear it all, I wish we could...