Here’s what I know in case it’s useful. 

In my meditation on the mind practice from TMI (which is actually proper technical Mahamudra instruction in disguise btw) – there is an experience called “awareness” that can be recognized as some sort of “backdrop” of experience. One can step back and become aware of this awareness while maintaining clarity on the current mind and objects within it, and for me when I was doing this practice I step back I noticed that there was a visual representation and a sensation in my mind of the “thing” called awareness changing size. It was in fact a tangible experience that I constructed. It would shift, seemingly change size, and then I would tell mind, “next level” and that experience of shifting awareness is then on a lower level, within the higher level mind. You do a few iterations of this and with a strong mind you will get an experience of mind as process that is very distinct and it’s a strong insight experience. You only have so much mental capacity, but when done correctly this experience becomes “direct seeing through awareness” which is a necessary precondition for the mind to experience mind as process. That awareness question can be investigated many ways, one like this and also other ways. 

Now people who do the noting practice will get a similar experience in high equanimity but the understanding of it is weak honestly and the entire Therevada path all the way up to Arhatship goes on an operating assumption of a true objective reality- true objective truth in sensations- this is wrong to be blunt and questions like “what is awareness” is kinda moot past a certain point- it seems what makes 3rd path hard for some is 1) ignorance 2) assumption of an objective truth to be found somewhere. 

For 2 assuming there is objective truth to be found in sensations has to be let go of and honestly if that notion seems crazy then one should get a better sense of dependent origination. With a strong clinging to objective truth in sensations, it’s subtle me-making and people can get confused and then when someone asks them “what is awareness” they give the company line “awareness is part of perception” as if there is some correct answer to that question, i.e. clinging to objective truth in sensations. If someone can accurately describe the sensate experience of a sensation arising and awareness somehow being baked into it, and somehow they have the notion that there are individual sensations themselves which come as packets with awareness stuck to each one, I would say that is immature knowledge and since 3rd path sensations are often described this way, no one really investigates this 

My experience has been that as insight deepens, there is less of a clinging to experiences of any kind, and this lack of clinging reduces the sense that there is a subject and an object. Or reduces the sense of separate experiences of subject and object. Less clinging-more experiences of non-dual awareness. Even to say that experience depends on subject-object existing, well that’s something I thought was true without question based on my experience of cessation, but I’m not so sure about that anymore. I am not sure because in states of Rigpa and other highly unfabricated states, there is a very close proximity to cessation, and often it’s as simple as switching on an light, but I think subject/object based perception may only be a thing until a certain point. 

I’m reminded of Dipa Ma. She had insight into the emptiness of Buddha, Buddhism, 3C’s all of it. There are some very curious things I know about the 3C’s that if you have that insight that’s what powers are based on. Since this is a high level forum- the gist of it is basically the 3C’s are a conceptual framework for experience and you can think of it like a three legged stool- you need a bit of a leg for each of the three legs for it to be considered a chair, but in practice if you detune one of the 3 C’s you get the others seem to intensify to stay at a status quo. You can, in late stage TMI, stage 10, take the 3C’s as an object – i.e. the mental representation of the 3C’s in subjective experience – take that as an object and through intention you can strengthen two and leave one at the absolute minimum- so you take the perception of impermanence and not self and intend to detune from the dukkha aspect. When you do this you can get insight into the dependent arising of the mental fabrications that are the 3C’s. 

My way of doing the jhanas and basically any perceptual state can be thought of like a tuning a radio really- when you think about it everything according to our current scientific knowledge involved vibrations of phenomena and the 3C’s are also a vibration of phenomena but they are a special type of highly protected reified phenomena in the minds of dharma practitioners- anyway due to the vibrational nature of phenomena and intention also seeming to have some effect on our perceptual subjective experience – to put it simply they are vibrations of phenomena and one can tune to different frequencies of phenomena. Awareness is one such phenomena but really it’s a beginner’s conception like Chris mentioned. 

In a simple way once dependent origination is understood then it’s just another vibrational phenomena really (but it manifests as mind phenomena… wait), and with a knowledge of how the mind works one can simply take a simple conceptual model – like “my brain can tune to any phenomena and detune any other phenomena by intention”. It’s not a crazy notion- people ignore things all the time and even conventional worldly folks know the mind can sometimes perceive something one way and be completely fooled about its own nature. Knowing how the different vibrational planes relate to how perception feels and how cessation and the mental planes work, my experience was that I had a intuitive sense of that and just started noticing things about how intentions would manifest in real time and I would simply follow the chain of dependent arising and whenever I suffered I would collect myself and take a different view, install it as a working model of reality, then test it, suffer, refine, etc.