Roon’s volume leveling offers the basics that I would expect - by Track, by Album, Auto, and None.
However, there is one more option I’d like to propose - by Medium or by Disc. In classical compilations and other kinds of box sets, the box set itself may be made up of various discs/recordings made at various points in time, mastered at different levels, all bundled together into a new release.
If I enable by Album leveling, the level is set based on the peaks of the different discs across the entire box set - so if one of the discs, which was previously released separately, and was not re-mastered and re-leveled for the compilation, is louder or quieter on average than the others, it will skew the leveling for the rest of the set.
What I would like is a “by Disc” volume leveling, so that rather than determining the level based on the whole “album” - e.g. the entire multidisc compilation - the level is determined “by Disc” or “by Medium” within that album.
Admittedly this is a niche thing, but for classical compilations which largely box up many discs of works recorded across different labels, at different times, with different orchestras, etc etc this would be very nice.