Sounds like a level of Formless jhanas (5th to 8th jhana) to me.
The ecstasy and joy of lower jhanas which you have experienced in
your younger days and described to me, will eventually fade as one
enters a higher level of absorption.
8 Levels of Jhanas:
1st - investigation (vitarka), analysis (vicara), joy, bliss,
one-pointedness
2nd - joy, bliss, one-pointedness, (inner purity, or internal
clarity)
3rd - bliss, one-pointedness,(equanimity, mindfulness,
insight)
4th - one-pointedness; (completely pure equanimity,
mindfulness,
neither pleasure nor pain.)
5. Fifth Jhana: jhana of boundless space
(anantakasa).
6. Sixth Jhana: jhana of pure expansive consciousness
(vinnana).
7. Seventh Jhana: jhana of pure emptiness (akinci, lit.
"nothingness" )
8. Eighth Jhana: jhana beyond perception and nonperception
(nevasannanasanna)
Nevertheless no levels of absorption whether form or formless are
ultimate. All these mystic states are created and conditioned by
the mind. They are impermanent and still within the sphere of
mundane realities. Buddha had abandoned 2 of his teachers who
taught him how to attain the 7th and 8th Jhana, because it did not
lead him to enlightenment.
At best such a practitioner of formless jhana, at the point of
death, abiding in absorption becomes reborned in the jhanic realms
of formlessness, and exist for uncountable kalpas of years. However
he has not ended his cycle of rebirth, and subtle defilements of
the mind may one day arise and cause him to fall even possibly into
the 3 lower realms (hell, ghosts, animals).
