12:5 by Pain of Salvation
Unplugged albums were quite popular at a certain time, when MTV still played some music, even if it was formatted into a show with an acoustic gimmick. This, like many of those MTV Unplugged albums, is a live performance, and it is an acoustic album. It even has bits and pieces of other things they've done before, but, unlike the Unplugged albums, they didn't just grab acoustic guitars, an acoustic bass, and proceed to play what is, essentially, a nearly identical arrangement of their original song.
In fact, you have to pick at it to discern the original piece in a number of places.
The album is divided into three sections: Genesis, Genesister, and Genesinister. The individual tracks blend one into the other. There are themes to this - depth not found in the aforementioned collections. Relationships, environment, war - all from a somewhat deeper perspective than one might come across.
The musicianship is superb. Harpsichord and grand piano and some cello in addition to the expected acoustic guitars and bass, often playing more in the realm of jazz or classical. Of course, that's one thing that doesn't really change between this and some of their non- or, more accurately, not-entirely- acoustic work. That, and their drummer/percussionist is phenomenal.
If you appreciate a bit of musical experimentation but hold your nose high in the air or jam fingers into your ear when someone mentions metal, this might be the PoS album to start with. If you like things hard and heavy, get hooked on one of the others first, then come back to this and expand into other musical styles. This album does a perfect job of showing how an all-acoustic band can be far more powerful and moving than most rock acts.