Actually, I almost implemented this a few times over the years in Quod Libet (https://github.com/quodlibet/quodlibet/issues/703 https://github.com/quodlibet/quo

Actually, I almost implemented this a few times over the years in Quod Libet (https://github.com/quodlibet/quodlibet/issues/703 https://github.com/quodlibet/quodlibet/issues/703), my use-case being mainly for classical pieces or DJ mixes... but never got round to it. Eventually someone kindly wrote a plugin that did pretty much this using what we all agreed was the best way: the under-loved `grouping` tag. Caveat: I haven't actually tried it yet... (Please file a Github issue if you try it but it doesn't work...)