An Ancient Observer is two different kinds of solo album in one. Most of its tracks adhere to the traditional definition of one musician playing one instrument; Tigran Hamasyan’s is the piano, and he plays it extraordinarily well. The other tracks invite the listener to question the definition of “solo.” Although Hamasyan is still the only performer, he incorporates expansive, immersive colorings via choral-like ambient vocals, pronounced beats and layered orchestral foundations. The lattermost are at times so enveloping, with Hamasyan utilizing both piano and synths, you’ll swear the keyboardist brought a full band into the studio.

Then there are those tracks that flit between the two worlds, among them the opener, “Markos and Markos.” As it progresses, from pastoral piano meditation toward a darker, more bass-heavy space, the weight and drama snowball in intensity; then, a full stop and Hamasyan comes full circle. But he’s already given notice that he intends to move outside of the lines. Other standard piano solos, “Fides Tua” and “Nairian Odyssey” among them, find more in common with Hamasyan’s earlier solo outing, 2010’s A Fable, than with 2015’s Mockroot, the Armenian musician’s last full-band Nonesuch release, or his two recent projects for ECM.

Surprisingly, the more expansive pieces on An Ancient Observer don’t connect so directly to those recent, more contemporary releases either; they signify another course altogether. The hypnotically swirling “Egyptian Poet” and the solemn “New Baroque 2” suggest the composer is reaching into some deeper global folk-music well for his melodies, while “The Cave of Rebirth” and the title track—both of them simultaneously foreboding and bucolic—settle into a world marked only by its self-defined borders.