Gheraṇḍa classifies samādhi into six types. He begins enumerating them: Dhyāna yoga (meditation), Nāda yoga (sound), Rasānanda (essential joy)…

These are not different types of technique but different “doors” or dimensions of the same state of absorption. Any can be the point of entry.

“Knower of the perfection of the perfected” — samādhi is the state of the siddhas, realized beings who inhabit freedom.