There were on the first batch many reports and complaints of loss of sound on one side but not a total loss of sound. Mine are from the first batch also and i had no issues at all but then it happened a good few months later. I figured it was probably ear wax blocking up the tuning filter over the end of nozzle, so i whipped that off and there was another filter underneath so i whipped that off too and now run them completely filterless. Then on initial release there was the promise of an app which arrived and then was removed and then it came back again. The app has the hearing test EQ tuning and you can also custom EQ. The filters were probably to dampen the treble from the BA which made them sound pretty good out of the box but also tuned for the masses bass wise, removing the filter adds more clarity and cleans the bass up and the EQ whilst not great actually does a good job tuning for your hearing.You can cheat the hearing test too, first do it genuinely then listen for a while if anything sticks out as peaky then lie on the test around that frequency or just tweak the EQ.
So remove the filters if you do not like the out of the box sound. That is the Mod.
Then do the hearing test to auto set the EQ and then tweak the EQ if your still not happy. That is the tweak.
I can run them on full volume and be satisfied and i do like extra loud in my IEM's, well any listening to be honest and i also do have approx a 50% hearing loss in both ears, so volume should be no issue to most people.
Battery life is genuinely great.
For the price they are fantastic value for TWS convenience.
I use silicone tips but not the supplied ones, nothing special i just needed a better shape and stiffness as in less stiff but these are personal preference things. Foam tips will also help dampen the treble if required.