Listening to the ED9 vs HDS1...HDS1 has more low end grunt than the ED9 w\brass nozzles. ED9 has more pronounced highs and more detail. Both are very good but I'd have to give it to the ED9 due to build quality and detail extraction while still having some clean tight low end. HDS1 is excellent but doesn't feel as well built. In your hand it seems light and plastic like although I've read it isn't plastic. Comfort though goes to the HDS1 due to them being light, small and very comfortable in the ear. ED9 is heavy in the hand and there's no question it's made of metal but once inserted is very comfortable to me. I also like the cable on the ED9 a bit more although I really don't like most, if not all the KZ cables...they can be sticky, springy and microphonics are an issue especially on the HDS1. Still out of all my KZ's ED9, ED10, EDSE, ATE, ZS1 and HDS1 my favorite is the ED9. Great price, impressive build and superior sound quality. JMHO.
ATE-S, ED3 Perfection & Acme on the way.