I am not an audiophile, I don't know what people talk about when the describe the sound as bright or dark. I usually rely on reviews and reddit to figure out what devices have good value and make my purchasing decisions based on them.
As most modern phones no longer has a headphone jack, I got FiiO-BTR3, a Bluetooth DAC so I can keep using my headphone. The size is small and I can clip it on shirt so it's a great portable device.
I have a pair of Sennheiser HD25 for 5-6 years and it's still going strong. I've replaced the cables multiple times over the years, which is cheaper than getting a new pair.
I love it, the sound is just so clear to my ears. However, before I bought these, I only use cheap earbuds so I don't think the comparison is fair.
The weather lately has made it a lot hotter to wear the HD25, I sweated a lot after 30 minutes wearing them. That's why I decided to get IEM for cooler ears.
I got Moondrop Quarks as it's cheap and I want to test out how IEM fits. The sound is ok but they don't fit my ears.
After trying Quark and reading a bunch of favorable reviews of Moondrop Aria, I decided to purchase it. Even though it's bigger than Quark, it fits a lot better on my ears. I also got Linsoul cable and SpinFit CP100+ to replace the stock cable and eartips, respectively. Overall, for the price, I really like Aria.