Verse 9

9.  Vaisvanara,  having the waking state as his sphere,  is the first sound,  A,  because this encompasses all,  and because it is the first.  He who knows thus,  encompasses all desirable objects; he becomes the first.

"Vaisvanara,  having the waking state as his sphere,  is the first sound,  A,  because this encompasses all".

Vaisvanara has the meaning  "all men",  and in this instance of its use it means  "all material creation"  ("encompasses all").
The manifestation of the material Universe is also the manifestation of  "Self",  to satisfy that first desire for mind and body  ("self")  through which to experience worldly knowledge.

"A",  the "waking state",  is the sound of all the names  (all the knowledge)  for forming the Universe.

"He who knows thus,  encompasses all desirable objects".

"He who knows thus"  is  "He"  that first desired mind and body.
Because Creation is to realise that first desire then  "He"  along with those objects of desire will be  "born"  into the Universe of his desires "encompasses all desirable objects".

"he becomes the first".

Because Creation resulted to satisfy  "He"  that first desired he will become the  "first born"  (Viraj)  of Creation.
Reference Brihadaranyaka Upanishad  1.  2.  1  :-
He created the mind thinking  "Let me have a mind".