You are of course correct, Mike. In fact, I literally said in my post up there: “What is true, however, and that is the important thing: like Mike said, the ‘Album Artist’ tag is what holds the album together; it is what unifies the album. So ONE ‘Album Artist’ per album, obviously.”
That’s why I said we don’t have an argument at all: we don’t really disagree, which is why there is no need to argue. Album Artist must be one value per album.
But there is more than one way to decide on that value. And I have spent quite a bit of time considering how to tag my own considerable classical music collection. I know how tricky it is, and I know there are many different approaches. When I started transferring my CD collection to digital files, I knew the better and more consistent my collection was tagged, the easier it would be down the road. In my experience, the key to successful tagging is “consistency.” As long as one is consistent, there are many different ways to approach it. I have found a way of tagging my classical music collection that suits me, but I believe there are also some general principles that may help those who are just starting to transfer their music collection to digital.
When I first joined the discussion on this ROON forum about a year ago, it was never my intent—nor did I ever think—I would spend so much time here discussing classical music tagging. I assume many ROON users have a digital music collection and have spent some time thinking about tagging and finding something that works. As have I.
That’s why I don’t try to convince anyone that my way of music tagging is the only way or that it should be done that way. But since this method works very well for me across many different platforms (including ROON), there may at least be one or two things that help others too. Especially considering that when I first came to this forum, I found myself in a thread with two specific questions suddenly entangled in a lengthy discussion about classical music tags, which had nothing to do with the actual question I asked. I found this thread very interesting, and it demonstrated what an active, lively, and at times quite opinionated place this ROON forum is. So I thought I fit right in. 
I also found the general level of decorum, insight, and articulation in this forum – even when very different viewpoints clash – very high and pleasant. Especially compared to many other forums, let alone social media. So I want to second John Coulson’s remark in his “ROON & Music in Retirement” thread: “Obviously Roon attracts the best of people!”
But back to the subject (yes, I’m quite wordy today, but it’s Sunday, I’m listening to Stravinsky and Haydn, and for some reason that makes my fingers race across the keyboard).
For my own tagging principles, I had several considerations that were important to me. Others may have different needs and so mileage may vary.
- Cross-platform compatibility.
I want my music collection to work even if I switch from ALAC to FLAC, from iTunes to another player, on Android, in my car – wherever. The tags should work.
- Organization similar to my physical CDs.
Ideally, my digital music files should be organized more or less like the CDs on my shelf, so I know where to find them (as I don’t have another catalog).
- Clear folder structure.
The folder structure should be so clear that I could find any album quickly, even via command prompt if I have to.
And since I found a system that works for me across the board and came to ROON a year ago, some people tried to persuade me to change my ways. I put some of their suggestions to the test and found: nope, I was right all along.
To illustrate my point:
I just pulled out a few CDs from my shelf that may illuminate the various considerations that come into play when tagging classical music, focusing on the “absolute essential” tags: Album Artist, Artist, Composer. All the other tags like year, label, copyright, orchestra, conductor, genre that many programs offer to varying degrees I leave aside, as they are often more “informative.” But the triumvirate of “Album Artist,” “Artist,” and “Composer” are essential for classical music tagging and greatly influence navigation within any collection.
Album 1 is easy. While it’s a box set, performer and composer are the same on all the discs, so it’s pretty straightforward:
Composer = Ludwig van Beethoven
Artist = Igor Levit
I guess most people would tag it like that.
Now it’s the “Album Artist” tag that caused the most discussion, with some insisting it should be “Igor Levit” (as the performer), whereas I (and some others) prefer the “Album Artist” to be “Ludwig van Beethoven.”
The truth of the matter is: do as you like, it doesn’t matter. ROON recognizes the album either way. The only difference, depending on how you curate your collection, is where the album is filed on your drive. The directory may be Music\Ludwig van Beethoven\Beethoven Piano Sonatas Levit or Music\Igor Levit\Beethoven Piano Sonatas Levit, but that’s about it.
I prefer this album to be found under “Ludwig van Beethoven,” as that’s where I would find it in my shelf, and that’s where I would expect the album to be in a record store (back when there were record stores) or library. But if anyone prefers the “Album Artist” to be “Igor Levit” and go by performer, that works just as well. It makes no difference. In ROON it works either way, so go with what works for you.
The second album is a big box set of all of Joseph Haydn’s symphonies, but the conductors vary. So how would you tag that? You can break down the box into individual albums, of course, but let’s just tag the whole box. My tags are:
Artist = [the actual performers]
Composer = Joseph Haydn
Album Artist = Joseph Haydn
Another option would be:
Album Artist = Heidelberger Sinfoniker
Again: either works fine.
When I originally bought this album, ROON could not identify the box set because it wasn’t yet entered into the databases (I got it very early). Now, a year later, ROON has correctly identified it. The fact that ROON initially did not identify this set had nothing to do with “Album Artist” tags, but only with the fact that the album was not yet in wider release and therefore not in any database.
The third album has many different composers, but the performer is the unifying element, so my tags are:
Artist = Maggini Quartet
Composer = [the actual composer]
Album Artist = Maggini Quartet
So that’s all pretty straightforward.
The next example is where some differences come in.
In my collection, “Das Knaben Wunderhorn” has Album Artist = Gustav Mahler.
As I said, I generally have my classical music collection sorted and grouped by composer rather than performer. I wouldn’t even know which performer to choose if I were to go by performer. Claudio Abbado? Anne Sofie von Otter? Thomas Quasthoff? Berliner Philharmoniker? For me, the Album Artist tag here is clearly “Gustav Mahler.” But again, theoretically, you could pick any other one as “album artist” and ROON would still identify the album correctly.
However, on the next album, it’s the other way around. The unifying Album Artist here is Hélène Grimaud, whereas the composers (Corigliano, Beethoven, Pärt) are just in the composer tags. So it’s just the same principle as the big box of British String Quartets up there. It doesn’t matter if it’s an individual disc or a big box set, same rules apply. To put it simply: where would I expect this album to be on my shelf? Or in a record store? Who is the unifying artist of that album, the “Album Artist”. Well, it’s Hélène Grimaud for me here.
And now, the last album is exactly like the OP asked about:
Two composers, Philip Glass and Alfred Schnittke. I just checked how I named the album, what ROON suggests, and what Qobuz has, and they all go more or less the same route. The differences are mostly delimiter signs. The title I gave this album when I originally tagged it is almost (but not quite) the same as ROON suggests.
As far as Album Artist is concerned, you can choose either composer, both composers, or the performer. If you choose performer, you have to decide which one? Gidon Kremer? Christoph von Dohnányi? Wiener Philharmoniker?
I have tried all the options and can confirm that all work. ROON recognizes the album regardless of who you put in as Album Artist, as long as the Album Artist tag is consistent. One tag per album.
Since you can also chose (for all or individually) which tags ROON should use, you actually have many different options how you want to tag your personal music collection. There really is this flexibility, and there is not “one way” you must follow to tag your music collection.
Since there is not one established way to tag classical music, the actual key is consistency. Whether you put Igor Levit or Gustav Mahler or the Maggini Quartet in the Album Artist tag is personal preference.
