That atyantika sukha — final, gradationless joy — is grasped by buddhi alone, beyond the senses; the one who knows it there does not waver from the real. Three predicates of the joy follow: atyantikam, atindriyam, buddhi-grahyam.
Shankara is precise on each. Atyantikam — without end or gradation; sense-pleasures rise and fall, this does not. Atindriyam — beyond sense-contact entirely; the body's instruments cannot reach it. Buddhi-grahyam — apprehended by the inner instrument when sense-contact is suspended. The wise one who abides in this state does not merely experience it; he knows it as his own nature, and having so known, does not fall away from tattva.
Madhusudana offers the panel's fullest analytical treatment. Atyantikam names the bliss as Brahman's own svarupa. Atindriyam excludes sense-based pleasure, which requires vishaya-indriya-samprayoga. Buddhi-grahyam excludes deep-sleep happiness, where buddhi itself is dissolved. The samadhi happiness is grasped by a buddhi free of rajas and tamas, carrying sattva alone — yet even this grasping is not the joy itself; the joy is the atman, the buddhi merely the unobscured medium.
Ramanuja reads atma-buddhi-eka-grahyam carefully: this happiness is not intellect perceiving an abstract absolute but the qualified self knowing its own joy as a mode of Bhagavan.
Madhva keeps the dependence-frame: the joy is rooted in bhagavad-rupatva, not in the jiva's self-sufficiency; non-deviation from tattva means non-deviation from the recognition that Hari is svatantra and the jiva paratantra.
Vallabha reads the verse most warmly: atma-sukha is Krishna's own prasada-given being; the knowing and the known are both in the order of atman-as-bliss.