I chose those headphones, as a pure audiophile, by reading and watching a lot of reviews. Notably, I saw that they are some the highest scoring headphones relative to their price in Crinacle's ranking. It seems clear that there is a consensus that those headphones have an incredible sound quality for their prices.
To be short, they completely met my expectations. I have a few comparison point of references of quality, the Beyerdynamic DT990 600ohms, the iBasso SR2, The Audio-technica AD500X and the AKG Q701 are the best ones I have I can compare to those R70X.
If they weren't so fragile(and leak so much sound too, although that's not something I would complain about because I understand it is a necessary caveat of the design for them to sound this good), I would listen to the R70X all the time. They are absolutely stellar.
The bass is strong, vibrating, breathtaking, a tad boosted but tastefully, not so much to ever be annoying and stomp over the rest of the frequencies.
Mids are on point, voices can be particularly beautiful, Sade's voice never sounded better to me than with those ... They do take a slight step back compared to the lower and high frequencies, but even on badly mixed hiphop that already has the voice behind the instrumental they are not muffled by them. They are not as forgiving as other headphones but still would quality them as forgiving, the precision, the fidelity they have in fact makes for an interesting listenning session finding issues that I couldn't notice much or at all on other headphones, like bad mixing, mastering, background noises, even grain.
The highs are also impressively good, way more appreciable than in the DT990 for instance.
The spatialization of course is grandiose, that open back design with the fidelity of te drives can hardly disappoint on that, although maybe the sound stage might disapoint at the first listen, it often feels closer than with other headphones probably because the driver is closer to the eardrum than on an AKG K7XX for instance, but the brain gets used to it and then the layering becomes in fact quite impressive. One of those headphones that convinces me brain burn-in is a big deal.
They do need an amp, that must be said, you can technically use and enjoy them from a phone, but you would need at least a somewhat powerful DAP to get it to the volumes where you will be having fun with music(and I don't listen that high, I let my xDuoo basic amp on the first power step and barely go above 2-3 o'clock on the knob with those. 12-1 o'clock on my Little Dot mk2, sometimes 3 o'clock), it's just "usable" if you need to a phone for instance.
So in conclusion they are totally worth the money imo, it's an hard competitor for this price, audio quality is crazy good, and they should be some of the most comfortable headphones for most(although I would rank the iBasso SR2 higher on this criteria) the only downside is the fragility of the frame, the plastic parts are quite thin, that sure is great for the weight and price I guess, but I personally wouldn't mind them if they weight more and using sturdier components. Fortunately Audio-Technica will sell you replacement parts if you contact them, and the repairs are usually easy, the design is well made for repairability.
I couldn't get parts where I live in Andorra someone from the community helped me and them to me, the audiophile community is awesome and you will probably find help if you need it!