Looking for an upgrade from Lethsuoer Cadenza 4

Hi, I'm looking for advice on what would be an upgrade from Cadenza 4. I own Sennheiser IE600 as second pair, I also had a chance to try couple of different IEMs from 200-500$ price range, I enjoyed some of them but still Cadenza 4 is my favourite sound signature and I'm looking for an upgrade now.

I can listen to Cadenza 4 for long time without exhausting my ears - sound separation is good, bass hits the right spot (I like bass but I hate punchy lower-mid bass that a lot of IEMs I tried produce and I have to listen to them on low volume) and vocals are clear and not overwhelmed by music. I think you can them balanced.

I'd appreciate some advice on what can be next step from this. Price doesn't matter.