What impedance did you get? I found going too high (75) kills the sound. On my Studio V I have a 30 Ohm adapter and that pretty much gets rid of all hiss while having a minor effect on the music compared to the 75 adapter. I still do honestly prefer not using it though but it's not so bad where it kills the sound like 75 ohms does.
I went for the 75ohm impedence and the sound became very dull.. It almost wipe off any bass left.