Naming a reference mix without SPECIFYING the instrument and the characteristics what to listen for, is as useful as saying: the best color is red... Or: this movie is great.
A reference mix is like a test-signal. You need to know, what you are "measuring" and explain that - in the case of reference mixes, what your setup specifically (does not well enough) reveal with that mix.
An example for a modern reference mix indicating a good transient response might be (not a problem in the analog days, when production and mixing was fighting FOR a more crisp sound):
"This mix is not too bright, but it has a too hard sounding tambourine. The transient sticks out too much and starts to hurt the ears at higher volume."
This might be an example how well the setup is reproducing transients in the upper mid and treble range.
Or a bass test for typical livingroom size bass problems:
"This mix has a very powerful punchy kick, but it tends to boom and muddy up in smaller rooms with problems."
Or a reference mix bass test, which is a test of the balance between bass and midrange:
"The bassline has a distinct distortion applied on the 2nd and 4th upbeat, strongly supporting the groove."
Or a stereo imaging test:
"In the intro the door opening is happening behind the listener."
It is NOT about: I like that mix.
Are you referring to my shared playlist? Frankly, this one consists of more "fun, subwoofer workout songs" I listen to when I'm in the mood to feel some bass rather than tracks to use as a test/calibration file. It's mostly a collection of songs I heard other people referring to as their bass test songs and some songs I listened to and felt that it has in some way especially noticeable bass.
I still use it as a "test playlist" a lot though in the sense that I use these bass heavy tracks to easily detect changes with different sub EQ settings and for that usage you preferably have heavy, repetitive bass lines. There are also lots of tracks with very deep but still detailed sub bass, which can be used to test if a subwoofer system/ the room can even handle these very deep notes. How much detail/pronounciation is there and how much does the room influence the bass (boominess, smothered detail)? Also how much kick and sense of pressure do different settings provide?
However, I can only judge these parameters relative to each other and not against "a reference", since these tracks are usually made of artificial/ electronic bass lines so we have no idea how it's actually supposed to sound like. For that we need some tracks with "real" acoustical instruments, where we generally have a better idea how those sound like even without having heard the mix in the studio it was mastered at. The problem is, there is not much music from "real instruments" that reaches very deep into the sub bass region. I have some of these kinds of tracks as well but frankly I find it hard to judge the sound of these since I am not a "real two channel guy", my primary focus is HT even though I still very much like to listen to music. I just try to tune my system so that it sounds natural/ not overdone in the bass to me with something like Norah Jones but still gives me some kick with more aggressive music like metal and some pressure feeling with the heavy deep bass lines in electronic music. This can be a very hard balance to strike though especially since I don't like to listen very loud.
Honestly, I don't quite follow what you mean with your comment about "reference mixes". I understand what you mean in terms of you wanting comments about what to listen for in a particular song but - to be quite frank here - this sounds a lot like meaningless Hifi mumbo jumbo to me... Sure, we can certainly tell if the recording and mastering of a record is of good or bad quality - even I, with my very modest surround sound system, can easily notice that.
However, when it comes to bass, how are we supposed to know what the "reference" is? We have no idea how much bass the sound engineer who mastered the track actually wanted us to hear when he mixed it in his studio - you'd have to sit in the exact same chair he sat in, listening to his speakers in his room to know that... every other speaker system on the planet will color the sound - especially the bass - at least somewhat. So to me, there are pretty much only two options to calibrate the bass for "real instrument music": it either sounds natural or it does not but knowing the exact amount of bass? Pretty much impossible if you ask me.
Sure, in terms of bass detail, you can certainly detect differences in mixes and in speakers/subwoofer- systems. If you compare two different EQ- settings, speakers/subwoofers or mixes against each other and you hear more details in the bass on one, you know that one system/setting/mix is better than the other but where does this end? How will you know that you now hear all of the bass detail you're supposed to or if you are still missing out on something?
Also, I don't think notes in the form you demanded like "in this song at 1:43 you should be able to hear a distinct subtle drum stroke in the background" are particularly helpful because anyone with a somewhat decent system should hear that stroke, it's just a question of how distinct/how loud it is - which we at home, testing that song, have no way of knowing of course. So all we can do here in this thread, is suggesting material you could use to A/B-test different gear/settings.
To be honest, I have a hard time judging this so called "bass detail" in music. I used to think that the meaning of "subwoofer A presents more bass detail than subwoofer B" meant that subwoofer A played some notes that subwoofer B didn't, which ime is not really the case. As soon as you have a "decent sub" even if it's only something modest like an SVS SB 1000, it should be able to play all the notes that are present in the bass signal. How much different bass notes you are actually hearing is probably more determined by the room and the EQ, so where the subwoofers are positioned, how flat of an FR you get from that position and how much room modes and long decay times muddy up the sound.
I think what people usually mean by "there is more detail in the bass" is actually a difference in the dynamics: If I did hear any differences between subs and settings it was like one would pronounce a note more than the other, which gives the impression of one bringing out more detail than the other but that doesn't mean that configuration B didn't play that note - it was just a tad more subdued - which would of course beg the question again, which one is actually more accurate?
Of course dealing with the room modes and decay times via multiple subwoofers, positioning and EQ can certainly "uncover" bass detail that was masked by "boominess" before.
This is a very difficult topic to discuss though since very, very few people have actually conducted controlled tests to determine audible differences like that. It would be very hard to properly compare two speakers or subwoofers to one another for example since you'd have to position them at exactly the same place (which of course is impossible at the same time so you'd have to make a compromise and position the drivers as close to each other as possible), EQ them to at least the exact same FR and have a way to instantly switch between both to determine if there even is a difference.
