Got my set last week, so far burned in for only around 70+ hours. As per the usual complain, the isolation is quite bad which imho defeated the purpose of having an IEM for outdoor/ on the move usage.
The soundstage is wide (without the usual in your head feel), with good detail and separation, but it's a tad bright and could be mildly fatiguing (your mileage might differ). The bass tighten up a bit after burning. Initially it was quite loose and irritating. Its forte is in instrumental and classical music. Vocal performance is slightly above average. For pop and rock music, the earphone does not have the snap.
Got the comply T400 (as recommended by Stereo at PS) today. While the isolation improved, the soundstage got much narrower., and I felt some detail and separation were lost. The bass got heavier, but feels abit muddied.
All this is expected with the improved isolation i guess. It's a trade off. For outdoor usage I would prefer the T400, due to the ability to use a lower volume, but if I'm in a quiet environment I would prefer the original tip.
Overall for its price, the Astello is an above decent pair of earphones, but note that many of its strengths are lost when used outdoor on the move (which is my pet peeve).
Disclaimer: Opinions expressed are my own, and your experience might differ due to our individual preferences. Cheers