Starline ill ill take as refferance for this comparison.
Kz/trn foam sounds a little Les bass heavy and more detailed in the low region and highs become a tat less bright there for the bl-03 sounds a little and mean a little more controlled over all.
Spinfit adds some bass to the starline performance with about the same detail as the starline tips on the low end front, but bass starts to be the prominent factor in the music on the bl-03 and shadows some of the mids a little.
Ibassio dc01 + Cema rx cable + bl-03 + spinfit = club like bass rulled sound! Love this combo for dance, trance, etc kind of music.
But Genck is right best is to try this your self because we all hear things a little different
Kz foam cost you 2 euro/dollar send:
€ 0,55 81%OFF | 3 paar (6 stuks) KZ Memory Foam Geluidsisolerende Comfortble Originele Oor Tips Oorkussens Oordopjes voor In-Ear Oortelefoon voor ZSX ZS10 Pro
https://a.aliexpress.com/mYUb8hWo
KZ starline will be 1 euro/dollar send:
€ 0,59 35%OFF | 6 stks/3 pairs Ear Earcaps Voor KZ Oortelefoon Siliconen Covers Cap Vervanging Oordopjes Tips oordopjes Oordopje Oor pads kussen
https://a.aliexpress.com/nlywE6Cg
NiceHCK spinfit will be 6 euro a pair send:
€ 5,34 37%OFF | 1 paar (2 stuks) NICEHCK SpinFit CP100 CP100M CP800 CP220-M2 In-Ear Oordopjes Gepatenteerde Siliconen Oordopje Innovatieve Technologie Oordopje
https://a.aliexpress.com/mj2v8p8y