The Rav often speaks about “havayah” (the force of existence) which is part of the 70 forces of the soul, and the Rav also discusses the power of “he’edair kodem l’havayah”, the “nothingness which precedes the soul’s existence”, which is also described as the power of levad (alone), the very essence of the soul, and which is also known as “Keser D’Keser D’Yechidah” [the “Keser” level within “Keser” of the highest point in the soul, Yechidah]. Recently Hashem gave me the opportunity to come across a teaching of the Rebbe the Reshab, who explains that there are three types of daas (understanding): A sense of being divested of the soul, a feeling of the general life-force of the soul which sustains the body, and the recognition of the soul as it exists above, where it exists as the source of revelation. Is this what the Rav is describing [when the Rav speaks about the highest point in the soul]?
No. The level of daas which is connected with havayah is described in the teachings of Chabad [as you mentioned in the name of the Rebbe the Reshab], which deals with chochmah and binah [two stages of intellect – the raw intellect and the detailed intellect, which are the precedent to daas, perfected understanding]. By contrast, we [Ed.: the Rav’s shiurim and sefarim] are dealing with the point of havayah itself, also known as “Keser” [when it is unattached with daas], which represents the point of the very first hispashtus [expansion of G-d’s spiritual energy] where the spiritual “light” of the Keser is contained in the “vessel” of the Keser.