I bought this about 2 weeks ago and it takes a lot of learning to figure out how to make it sound its best. It needs to be turned up about ¾ of the way from full volume(I used the wired connection(usb c to usb c)) and your source(mine is android Samsung phone)) at very close to full volume. It comes with a usb a to usb c cable, so you may need to buy a usb c to usb c OTG cable to use it with you phone or specifically c to lightning if you use that type of apple phone. Then let it warm up for about 20 minutes to 40 minutes before actual listening like this and then still leaving like this or reducing to a more acceptable level to you where tone is still ok. It depends on the efficiency of your earphones or headphones. It has very good imaging and balance of all frequency levels. All instruments sound well represented and their presentation or location seem pretty fine to me. This a very nice device, way, way better than it's price should allow. I'm very impressed and satisfied and of course lucky to find this! I always end the day with listening to it, I can't go without listening to it what I mean. I don't believe it is missing anything in the sound quality spectrum. You just have to experiment with that volume control and bass switch(or leave the bass switch off for more natural sound) to coax it out of it, ask it nicely. Lol Oh and to experiment with source volume too. Be patient, it is such a great device! I have yet to try out Bluetooth, but it has the latest 5.3 and the best chip for it too, so I have the utmost faith in that being pretty fine too and I'm very anxious to try that too. If I can remember, I'll update how it goes. It is one very beautiful device with a great style, the front is a thick glass that shines greatly and looks so good and the back is a black with a lighter shade in kind of a checker board type of pattern that looks really good on it. For my listening I used the 4.4mm connection. There is also a 3.5mm which I did not use. The bass boost function is a nicely done boost and is spread across up through into some lower mids too, it is really nice.
Battery life is very good, don't let it run out to completely empty and they say to not let them charge to 100% and they'll last even longer in their overall lifespan. But this is good to it's specs.
Thank you so much Linsoul and CVJ!
EV