as per your pm
hf3 v ma750, well they are very different. the hf3 is a deep insertion, high isolation iem and the 750 is a shallow fit. net everyone loves the brain implant depth of etys. sound wise its rather neutral, ie its very bass light for most people. so much so that id say unless you know thats what you want then its likely to come as a real shock to the ear.
the 750 is super sturdy and solid. its very comfortable fit wise and has an acoustic signature thats more typical. ie its got bass that will be more what people are used to. its very good audio quality wise too.
so id say if your having to ask about the two then unless you have a pressing need for extreme isolation then the sensible option is go for the ma750