Navigating their entire output would be difficult, and likely little of it would stick in the memory.  Their recordings are superficially similar, each reflecting subtle facets of an obscured looming structure.  More than compositions, their pieces are functional tools for mental focusing.  There is no linear evolution or evolution within the music, rather a continuous attempt to fully resonate the body cavity and attain the mental state resulting from repeatedly expelling the breath in a controlled fashion.  The songs are 'mantras' in that the singing is a sequence of  irregular phrases, each enunciated on the same low pitch.  Sometimes the end of a phrase in punctuated by a 'huh!'.

With each disk containing a single marathon session in the form of a 50 minute track, we have two uninterrupted journeys into the core of mind, consciousness, attention, and the essence of what 'Phurpa' is.  The two long tracks do not remain completely unchanging for their durations, breaking naturally into sections with lesser density, but it's clear that they were performed as a whole, and they benefit from the gradual, sustained immersion of unbroken intentional activity.
The sound is emanating from palpable pitch blackness, as if the band performs in some sanctuary space removed from all time.  Due to the group's dedication to acoustic primitivism, I'm certain the reverberation within the space they record is natural.  By its essence I would guess it is subterranean, although it is possibly some kind of cathedral or stone building as well.  Though the sound is ghostly and luminous, I would guess the room is actually not of monumental size.

There are moments where I hear something like a cymbal, scraped metallic percussion, as well as a resonating baritone horn which could be a conch shell or primitive traditional instrument.  Unlike the other Phurpa recordings I've heard, there's even some actual drums, though they're far in the background, sounding home made as well with a dull thud of tightened animal skin.  90% of the sounds on the album, though, are voices.

As this is the 3rd Phurpa album I've heard, I've become used to the supernaturally deep, beastlike dry vibrations of the vocal tones, and what begins to strike me about their work is the truly bizarre nature of its pacing and structure.  Connected to some glacial, dilated sense of time, they are so patient and yet so whimsical, sustaining a drone as a group for upwards of 9 minutes until a sort of abrupt falling away into murmuring, only for one member to begin anew on their own, leading the others to join in again.  It's like listening to a chorus of frogs in the pond at night, one moment startled silent by some danger, then inevitably resuming again.

It is difficult to distinguish this album from the other 2017 Phurpa release I am familiar with, "Gyer Ro", also a double album.  Both are perhaps more easily differentiated from 2009's "Trowo Phurnag Ceremony", which contained shorter pieces, more of a close mic'd, immediate sound than the washed out cave ambience heard on the newer albums, and a more rhythmic style of singing and enunciating.  "Ya Tog Rid Pa'i Gyer" and "Gyer Ro" are much like reconfigurations of the same elements: the nebulous, cloud-like unison drones, wailing conch shells, vast gulfs of silence and lengthy track durations.

At this point, I can't exactly say whether I've benefitted from hearing a 3rd Phurpa album.  Though I feel the sound they create authentically originates from a state of trance, it's not always possible for me to follow the group where they are going.  In a sense, their music is opaque to recollection and understanding, "Ya Tog Rid Pa'i Gyer" containing a thoughtless droning blankness in much the same way as "Gyer Ro" does.  Unless I've attained the perfect meditative space for listening, I find it difficult to focus my mind on the sound.  It would certainly be easier to attain such a trance by performing the singing myself... but indeed, few would have or have had the discipline to immerse themselves as deeply in such a trance as these individuals.  In their unapologetic, single minded resolve, they remain an enigma.