I'd like to start out by saying I'm not an Audiophile, but I do have a few methods of getting 80% of the way there. I have some FLAC, I have a pair of open Audio Technicas I use for gaming, an old pair of Sony MDR's, and an H2 I can use as a DAC. I've also tried a pair of Grado sr80s and I've tried portapros and owned HD555's for like a decade.
Cheap stuff in the Audiophile realm, but hey, it works.
These things are mid-treble heavy, with punchy bass, detailed as hell instrumentation, but feel like a rather small, enclosed space. They are in no way echoey. If I could compare them to anything, they're like an IEM pair of Grados with more detail and less shrillness. Fantastic for Jazz, Metal, Hard Rock, anything with a good boom and some highs to send it with. Early Mastodon riffage is goooOOOOoood.
I put some Floyd through them and I felt like I had a very pleasant experience. Every instrument stood out in its own space. I put my DAC to them and quickly found out I didn't really have to, but it did bring up some of the lower bass for better or worse.
Should you buy them? I'm not entirely sure. They were $35. I'm sure something... $70 might knock the pants off of these, and some might say "Well it already stands with $70 offerings". It may, I don't deny that Sennheiser iems probably aren't good. The trick is figuring out which of the few million Chinese ones are just as decent. Threading the needle with Ai Amazon reviews and Audiophile influencers gives you a weird mix of truth and lies and you kinda have to sort it out for yourself.
But, if this brand pulls this off at $35, imagine $70, and that's where I'm aiming next. These will become my new Steam Deck earbuds, but for now, they're great for FLAC and enjoying my music. They're quite fun sounding iems. Put some riffs through them and ride the rollercoaster.