Audio quality concern

Audacity 2.4.1. Windows10. Recording an audiobook from a mid-size walk-in closet with clothes on sides and moving blanket behind the mic and over the closet door. 6 months into the project. This is my first audiobook project.
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The Large Diaphragm Condenser mic used for the last 2 months is Equitek Cad E100S, previous mic and still owned is the AT4050CM5. The signal from the microphone goes to the MixPre 3 and I take the recorded files on an SD card to my Windows 10 computer. I’m fighting artifacts at the end of words that seem harsh going into new words like ‘clunk’ noise, some static when speaking, and words that seem boxy and strained even, though I record approximately between 20DB and 12 Db as advised. Also in the middle of words are issues. I need some help in determining if the audio is a fault of my vocal technique, the room, the microphone, or a combination.

(I have learned that sound issues aren’t always the mic’s problem but voice technique and room conditioning.) One time I am elated over audio quality and think maybe I’ve stumbled onto the best work process, the next leaves me scratching my head, perplexed. I’ve turned both the mic and mix pre high pass filter on at the same time (is there a problem with using both together?) and have repositioned the mic a number of times. I stood for a while when recording and now I’m sitting to see if it’s better. Currently, the mic diaphragm is eye level so that I am not speaking directly into it, and I am slightly off-centered as I read the script. I know the Cad is a super-cardioid so I try not to veer too far off, can’t in that closet anyway. Please also answer if it hurts to have the Mix Pre low cut filter and the Cad mic highpass filter working simultaneously. Or should it be one or the other? ACX check will show between -75 DB and -89DB when selecting an entire track in audacity with several seconds of quiet room tone but individual audio-only selections within the track produce -37 to -69 in the ACX Check. Does Audible check small sections of audio or the whole track with the initial room tone? Thanks in advance for any help. Caveat: I live in the Salt Lake City area and it is very dry. Could this affect the mic? Could there be a mic defect? Some Cad E100S mics have been known for becoming noisy and erratic over time… labeled a quality control issue. When I first got it the audio was silky smooth and still is off and on. See pics and audio uploaded.

Sorry, sent the wrong clip. Here is the correct one and much shorter.

Regarding the technical details of that audio file, it would be worth carefully reading through these specifications:

Not all publishers are as strict as ACX, but if you pass ACX standards then you are likely to be fine for any audiobook publisher.

Yeah, I’ve read through the ACX link you provided many times, and definitely before starting the project, as well as viewing multiple ACX videos. I’ve also searched through much of the Questions and Answers. Now, the file originally sent in this post was the incorrect one. The one that followed is a short clip. I was looking to identify the reason for the clunky artifact like quality at the ends of words, as in whether it is mic related, technique, room, or all of the above. I’m about ready to return to my AT4050CM5 as it is a normal cardioid pattern where the Cad is a super cardioid. This all started happening recently. I’ve had many chapters come out fine. I thought someone might be able to identify (in the second clip of course) any issues I might be able to resolve.