Let me go back to the beginning at take this from a different angle.
We have many different applications of the word "Reference".
Relative to Reference Levels, the reference in question is simply an accepted standard. Where do you stand relative to the predetermined number we are using as a standard reference.
In this case, Reference Levels simply means that any AV system is calibrated to a defined standard or reference level, which is, indeed, 85db with 20db of headroom. Though the reference for the Subwoofer is 10db higher at 95db with 20db headroom.
However, you can have Reference Amps or Reference Speakers again in the context of a quality of function standard. Many audio reviewers have what they call their Reference Equipment. Though it may not be the best, it is the standard that they are familiar with and that they use to compare other equipment to, as is, how do these speakers (or amp or other) compare to my standard speakers (or amp or other)?
Then we have, and I think this is important to the discussion, Reference Quality. These are amps, speakers, Turntables, and CD Player, etc... that are the standard by which all other equipment is compared. This is truly the best of the best. When you have Reference Standard or Reference Quality equipment, regardless of what that piece of equipment might be, you have very very very high quality equipment indeed.
So, moving back to Reference Levels, that is NOT a measure of quality. You can buy the crappiest Walmart 5.1 system, and it can reach Reference Levels, which is not really crazy loud. But, reaching Reference Levels does not mean a crappy Walmart 5.1 system will sound good, only that it will sound loud.
Equally, a $20,000, $30,000, $40,000 Home Cinema can achieve both Reference Levels and Reference Sound Quality.
Though opinions vary, I would say you have to reach about $5,000 or MORE to get near Reference Sound Quality in speakers. I can think of several speakers near $5000/pr that are Reference Quality enough for me, and many in the $5000 to $10,000/pr range that are as Reference Quality as I could ever possible hope to need. Bearing in mind, that you can easily spend $50,000 to $150,000 on just a pair of speakers.
So, independent of Reference Levels, you can certainly hear the difference between common garden variety good speakers, and true Reference Quality speakers. And you can most certainly see the difference in the price.
The two things are really not that connected - Reference Level vs Reference Quality.
Good speakers sound good at any volume level.
Reference Quality speakers sound superb at any volume level.
Really more than hitting specifically Reference Levels from your system, far more important is finding a level that best suits your listening experience. My system, which is a Stereo can get quite loud for movies, especially action movies. My system is also capable of reaching sustained average levels of 100db, with plenty of volume control to go.
But, I would say non-action movies is in the 75db range, and action tend to run in the 85db to 95db range which is loud.
You can't just consider the volume, you have to consider the space. In a very large room with good acoustics, higher volume levels are possible, but to take that to the absurd counter extreme, 85db in an empty closet is likely painfully loud.
So, if you have run Setup (Audyssey, YPAO, other) that calibrates the volume control so that at 0db, you are averaging about 85db. That is your Reference Level. Once that is done, simply listen to movies at whatever level is comfortable for that particular movie.
As to low volume listening, there are speakers that have more presence at lower volumes than others. But, choosing a speaker based on that parameter is difficult, you have to listen to a lot of speakers a lot of times, to gain that sense from a speaker. Generally, a speaker that is brighter, more forward, with a greater sense of midrange presence, with greater sound stage is likely to be better at lower volumes. Best guess - Dali, Focal, Monitor Audio, Dynaudio, etc...
Generally, a comfortable, though not quiet levels, I don't have a problem with most speakers I have encountered.
For music, my typical listening level is about 75db average at 11 feet. That's comfortable, but not exactly quiet.
So, the core of what I intend to say was to make a distinction regarding how the word "Reference" was used.
Reference Level simply means calibrated to a fixed predetermined level for movie watching.
Reference Quality, in any equipment, refers to the highest standard of quality.
You can have Reference Levels with virtually NO quality and you have have Reference Quality at the lowest of functional volume levels. Never the twain shall meet.
Hope the helps.
Steve/bluewizard