There is plenty to read out there and there’s nothing wrong with reading, but I think that you know all you need to know right now. You said you like quality sound. To me, that means when you listen to certain headphones, you think they sound good (quality) or less good (lower quality). That’s all you need to know. If more audiophiles would do that they would be a lot happier. But instead, they read reviews and articles about what other people tell them is good, buy it and then get stressed out when they can’t understand why they don’t like it. Just giving you another perspective.
The most important parameter to headphones (and speakers too) is frequency response - that is, how smoothly and perceptibly even the headphone reproduces the audible frequencies (20 Hz - 20 kHz). Everything else - driver material / type, headphone construction, etc. - can be considered 'window dressing'.
Currently, research relating frequency response to sound quality has produced the Harman Target curve. This is a frequency response for headphones that was obtained by measuring the response of sonically neutral speakers in a well-treated listening room using a head / torso simulator and further refined by listeners (trained and untrained) over a series of experiments. This would be your best shot at hearing a 'reference' or 'neutral' frequency response.
Several headphones follow the Harman curve - the AKG K371 ($149), the Mark Levinson No.5909 ($999) well as the Dan Clark Audio Stealth ($3999). Any of these headphones can be used as a reference. Importantly, there's little correlation between sound quality and price. For example, I've owned or listened to plenty of expensive headphones from the HD 800 to the Focal Utopia, STAX SR-009 and the DCA Stealth. The headphones I use daily are the AKG K371's. They sound very close to the Revel Ultima Studios I use in my stereo.
If you don't happen to like the sound of headphones tuned to the Harman curve, use an equalizer to find which frequencies need a boost or cut. Using your adjustments along with measurements of a headphone's frequency response can give you a better idea of which headphones would be better suited to your personal taste (if you don't feel like using an equalizer is a permanent solution). This frequency chart can help you in that process - EQ Cheatsheet.
Here's some more reading on the Harman curve in case you're interested:
I agree that Harley’s book is probably a good place for you to learn many of the concepts and jargon that describe and embody high-end audio. But the BEST thing you can do is go listen to as many headphones as you can with your own music, and then all these aspects of sound will become more relatable and — most importantly— you’ll start to form your own opinions on what sounds good to YOU, and in the end that is all that matters.
Try to hear somebody playing music live, whether it be at a bar, a nite club or a musical instrument store. It doesn't matter if the musicians are good. Just try to get an inkling as to what musical instruments actually sound like. Of course, if you or somebody around you does play, so much the better. You can also try going to a mall or department store. What do the customers and salespeople sound like? Take note as to how sound varies when it comes to how far away it is, and whether the setting is echoed or "dry.". In other words, set about training your ears.
The real learning that is required in high end audio is to be exposed to the terminology then examples of real sound, and in reproduced equipment. Over and over again.
I have been learning about sound and music / reproduction for fifty years… I continue to learn. I only got rhythm and pace down about ten years ago, although reading and listening all that time. Ok, maybe I am slow… but it is a process of reading and exposure.
I'm sending you to the conservatory - listen and remember well how real acoustic instruments and the general atmosphere sound (you can write down impressions on paper) ... and then visit the store with headphones - turn it on and compare ...
only your ears will give an answer - what to buy and what not
"Audiophile" is not a term that denotes any particular level of knowledge or any particular level of knowledge about this hobby. There really are no standards for many of the terms that you refer to -i.e warm for example is a term that refers to a quality of audio presentation that is more relaxed and mellow as compared to "in your face", blaring, etc. The real key to being an audiophile is finding audio components that produce the sounds that please you. You will never get official recognition that you have become an "audiophile" -it is something we self appoint ourselves as becoming an "audiophile" and what the various musical qualities you name above actually mean or refer to is somewhat subject to each one in this hobby.
Find equipment that you like and enjoy, be prepared to repeatedly spend more that you normally would like to spend to improve your system and the sound you enjoy and you have then become and "AUDIOPHILE" - welcome!
There area number of definitions of audiophile. My favorite is: someone who’s audio system cost more than their car. I have qualified in that case since the 1970’s… typically 2x or more. It isn’t a term about exact sound quality, it is about commitment to the pursuit… definitely in the fanatic category… in pursuit of the absolute sound.
My partner of over 35 years jokes about there being normal dollars and “audio dollars”. One hundred dollars equals one audio dollars. I will not pay a couple hundred dollars for a new lamp… but $5,000 for new interconnects… no problem… a bargain.
There were early editions of both Stereophile and The Abso!ute Sound where J. Gordon Holt and Harry Pearson respectively presented a glossary correlating frequency ranges with descriptive commentary (eg. bright, overly bright, dominant midrange, etc.) I've actually discovered a very early edition of High Fidelity magazine where Hans Fantel did the same. See if you can find one of them online.