The 7Hz Zero has a very fatiguing treble, I gave this one to my 17 year old daughter and she seems to like them. She could choose between the KZ Zex, Zvx or the Zero and she wanted the Zero. I was just happy I got rid of them. The Krila sounded to flat and even the switches could not help. It was lacking in bass and mids. The Chu 2 on the other hand, although not bass heavy, has a very enjoyable bass and also the mids and highs sound good. It’s the balance that make them enjoyable. Although I have a lot of IEM’s that are more expensive I keep using them before I go to sleep. On the bed with my eyes closed I really enjoy them and can’t believe they just cost about 20,- euro. I can take one of my 2 Hidisz IEM’s or even one of the HiFiMan IEM’s but strangely enough a lot of the time I end up with the Chu in my ears.How does Chu 2 compare with 7hz Salnotes Zero (assuming you still have it)? Also, what'd you not like about the Krila?
With all my IEM’s I use aftermarket cables (usually 16 core with 4.4mm pentagon) but with the Chu I use the supplied cable. If I had to guess I would say these are IEM’s that cost between 80,- and 120,- euro.
In my opinion the Chu 2 performs well above its price tag and I can recommend them. If you want something (slightly) better you can get the RE800 or the MS3 but you have to pay a lot more.
I hope my personal opinion helps.