No offense taken, questions are always welcomed here...and while my background is about as far from electronics and audio as can be, here's what I've managed to cobble together as I asked myself the same questions you are asking now.
I start from the premise that what I want from a DAC, is for it to do its job with competence. It doesn't have to think, it simply has to follow its instructions to recreate an electrical signal from a digital one. Nyquist Shannon Sampling Theorem tells us that as long as we work within its constraints we can recreate the original analog waveform with no loss of information. As hard as that was for me to process...turns out to be true. If there is any magic to be had in digital audio, it is in the recognition of the magic of N/S.
In other words, we don't need to add or subtract anything beyond what the math tell us...which generally has to do with effective reconstruction filtering to get rid of 'aliasing' or potentially misread digital samples which could create unwanted erroneous errors. As long as those functions are performed properly, the DAC can simply be measured along accepted standards by measuring the electrical signal it generates (which isn't a sound yet...it's still just a signal until it reaches your speakers) and see how clean that signal is. What has a chance to be added or subtracted through this process would be signal errors that have nothing to do with soundstage, punch, slam, front to back depth, or any other well and overused buzzword bingo slang of the day which happens to be popular in the standard audio review world, or have anything to do with musicality. It would have to do with noises and distortions.
Since we can compare the electrical output against the input signal with relative ease...we can simply measure these noises and these distortions to see what we might be able to hear, or what is beyond any realm of human senses. Once we know what the levels are of these unwanted signals, we can determine what might come to bother us or even be remotely audible. Instead of using the old fallback of -120 dB being unquestionably transparent as the reference (which I am not arguing...of course it is transparent), how about something to relate what that actually means in the real world.
For example, I love this simple illustration put together by
@RayDunzl .
View attachment 36015
Once you get beyond maybe -80dB (@ 6 miles away effectively) to -100dB (coming up on 80 MILES away...), how much do you believe that is going to impact anything remotely audible?
We will consistently hear claims of those who can EASILY, OBVIOUSLY hear how much cleaner, (fill in endless stream of random audio kinds of words here)...some DAC is, and if one expresses suspicion of these claims, we hear how it's just that our systems must suck, our ears need help, or some other standard fallback... Often followed by, "even my wife in the kitchen could hear the difference."
Thing is, I used to be right there with them in hearing all of those things. I KNEW I heard differences. What I did, which is what you are doing, is decided to try to educate myself and use my own ears rather than rely on uncontrolled, completely subjective reviews from people who SELL AUDIO PRODUCTS. Bought a moderately expensive DAC...came on here and was relieved to see that it had measured very well. Good for me! Except...the more I read, the more I was learning that maybe it measured well, but it was suggested I couldn't tell it apart from my AudioQuest Dragonfly Red, or even my 20 year old receiver if I were to match the output voltages between them, so as not to give one or the other a loudness advantage (old trick used by any audio salesman....people prefer louder to less loud almost universally), and have someone switch between them without me knowing which was playing.
Wow...humbling...embarassing...WTF-inducing...
Then...ok...on the plus side...I can still send this thing back. And, and even bigger plus is that I can stop worrying whether I need to now buy the next new expensive thing that someone tells me moves the bar even that much higher, and can allocate my resources where it might matter to me in my room with my speakers and my ears.
DAC's are not magical...they do not create music. They take a digital signal, follow instructions, then send out an electrical one. Nothing more...nothing less.
If I want certain sound features or characteristics based on certain recordings, mood, purpose... I can easily add them through DSP. The last thing I want in a DAC, is for it (the designer) to presumptively decide the original music as recorded isn't really what I want...I want HIS version of how it and every other piece of music should be filtered to his taste.
Well, I don't.
Same thing applies to most of the other profit centers in the 'audiophile' world. Cables of any and all types in particular are where you are really getting bent over and laughed at...
Basically, keep reading. It won't take you long to learn from the University's worth of teachers you've got on this Forum.
I'm sure I've bungled something pretty thoroughly in that meandering mass of words, but you asked sincerely and I wanted to give you a sincere answer from this recovering AudioPhool.
My name is Woody, and I am a recovering Audiophool...
Cheers. Please keep asking questions. Whatever the level of detail you are looking for, you can find it here. Without the snake oil chaser...