Overdue opinion on this and in reply to
@actorlife
yes the ATR needs a bit of amping or a more powerful DAP. After switching from a Shanling M1 to my Fiio X1 II I find the bass is a bit more extended and defined, while soundstage also seems to become wider.
Not too sure if just increasing the volume will help. Because while I tried that for the M1 the sound signature was really flat and smooth so that may be why the improvement wasn't much.
The ATR goes fine on my X1 II at around 36-40/100.
ATR is better for general listening as the ZS3 bass is a bit bloaty even with starline tips. However I do miss ZS3's energy and slightly more defined mid to upper register as my ZS3 has QC problems (intermittent audio).
My daily is currently the Creative Aurvana In-Ear 3 as I got this dual-BA real cheap second hand, though bass is severely lacking. I have a Brainwavz B100 on the way and am not decided on whether to try the Mi Earphones Pro HD since I prefer overear designs.
However if you can save up longer, I think a good DD endgame that isn't too expensive (ahem Mee Pinnacle P1 or Campfire Lyra II) is the ATH-E40. If you can stomach the clunky design it's a pretty good versatile DD that is more dynamic and less bassy/one-trick-pony as the more popular ATH-IM70/LS70 range. I may get it too as I always worry about reliability of Chi-Fi...