I received the 75ohm adapter earlier today. Finally I have some time to listen to them (right now) and so far I am very very pleased! Er4p + 75ohm adapter > Meier Audio Quickstep > Hisound Studio 3rd Anniv. > The Beatles > Abbey Road
The biggest surprise so far for me is that it is quite involving with the music. I've been tapping my feet and my hands quite a bit.
Fit: I received the er4p yesterday, and I spent most of the time just finding the right fit and because of the faulty jack, I had to fiddle with that too. I settled on a pair of long Comply tips I had from an old pair of Westones. I am able to get a deep insertion, sound is balanced from both sides and comfortable.
ER4S is the only IEM that I have which makes me feel right home as soon as I have it on. Quickstep is the best pairing I had with ER4S.
Happy listening sir :)