Unsuccessful Materiality-at-Hand
Adorno starts by noting materiality-at-hand was thought of as a kind of way outside of the categories of the subject. In this way, just like phenomenology, Adorno notes how fundamental ontology is an unwilling heir to positivism: in light of the elimination of the subject as an Idealistic ornament the philosopher can turn to the things themselves. But in Heidegger the things themselves do not even have a form. This overflowing of the subject gives motivation to an idea that that transcendent is immediate, and not subject to the categories. Adorno equates this with an unknowing romantic militaristic bravado.
The subjective mediations are taken care of by treating them as structures of consciousness prior to reflection and mediation. This fails because in the process all distinctions are erased. This, in conjunction with the distancing from empirical inquiry, means that Being hangs as a free-floating X, like the thing-in-itself.
This absolutely inexpressible X is the most real thing. But in the spirit of the aporia of Being if we reflect upon the concept presented then we see that Hegel’s judgment follows through: Being is equate-able with nothingness, and Adorno claims that Heidegger was not unaware of this. Adorno also wants to make it clear that for Heidegger this is a kind of positive feature of Being rather than a nihilistic nothingness at the center (but it is, for all that, inexpressible and captured by the endless repetition of Being).