Bass is OK, tight but not low as in the frequency you get in a woofer.
I replaced the tips with some comply ones I got from amazon a while ago and that did improve the low frequencys a bit as well as massively improving the comfort.
All in all very happy so far but I dont have a massive frame of reference.
IEMs I have owned
Samsung s8 AKG's (good)
Jabra sport pulse (good)
Skull candy (meh)
Beats (meh)
Old apple pods (crap)
These I would rate (in comparison to above) as excellent.
There's tons of details, and more than enough base.
I have yet to hear a earphone / headphone that carries the low frequency's as the old 17' MTX woofer I used to have in my car when I was in my 20's.
I would say base is similar to my sennheiser hd600.
Been using them vanilla, will tweak with eq eventually and see if it is better.
But so far , doesnt sound like it needs more.(early days), although my taste is for a neutral sound signature, ie Beats vs Bose, would choose Bose.
Hope that helps.