I've come to really love the BL-03 and its tuning for its warm bass. Makes metal, rock, and other hard hitting genres just so satisfying and fun to listen to. Took a lot of experimenting between hook and normal bullet style placement as well as playing around with different ear tips ranging from some double flange, the Spinfit cp100, and some memory foams to really enjoy. Found that using memory foam tips with a hook style fit and the Salnotes 7hz Zero cable to be the most comfortable, although I still experience discomfort after several hours of use if I don't place them right. The Yinyoo 6-core worked fine as a replacement although I wish I had gotten the 8 or 16 core because they tangle easily.
Even after using the Salnotes 7hz Zero and Moondrop Chu I still love these because songs sound really fun and impactful. I frequently find myself struggling to put these down because songs with that warm bass is just so satisfying. I use the LG G8 ThinQ with its Quad DAC when I really want to just jam out. I've yet to get an apple dongle for my computer, although I don't think these need a lot to drive or get the most out of.
I love these but I can't recommend them because I feel like there are much better options for both price and bass/detail like the Truthear Zero or Salnotes 7hz Zero w/ GizAudio's EQ. Definitely could've afforded a better starter IEM like the Tin T3 Plus, or if it were out, the Truthear Zero if I didn't sink the additional costs of finding the right ear tips and cable replacement for these. The Salnotes Zero work great as an in-between for the Chu and 03 with its great detail and stronger bass (only with GizAudio's eq) but still isn't as satisfying as the 03s' bass. As such I use the 03 when I want to have more fun, otherwise I use the Zero for everything else and Chu for when I leave the house.
tl;dr 03 has a very fun and satisfying warm bass sound, but there are better options for the price and sound nowadays. Yes the stock cable is abhorrent.