>>106984817
>Is it diminishing returns from now on if I buy more expensive IEMs?
sound quality is basically solved with $5 IEMs so it's not even diminishing returns. There's just no correlation between sound quality and price.
So technically there may be something that will sound even better than vivace for you but it's impossible to predict what will.
So just EQing it a little bit more to your preference might be better