I agree, I only enjoyed it with certain music. Z5 sounds great with everything comparatively. For that reason alone the Z5 is a better buy as it is more versatile.
Yeah, I usually hate bass heavy signatures but Z5 is really growing on me. Something about it is just really addicting, and I am hoping to get the upgraded Sony cable for it to see if it changes the sound any.
I am using the Z5 out of the apogee groove and the bass is MUCH MUCH better than out of the rest of my gear. They really need an amp to shine, its not even a debate at this point.
But I am also a huge fan of more bright signatures thanks to the Venture Electronics Duke iem, which is bright vivid and analytical. Quite different from the Z5, and variety is always good
I am eventually going to pick up both the EX1000 and 7550 as I am somewhat of a sony fan and I would love to have the entire collection.