My pleasure. But why the CD900ST? I know it's the standard in Japan, but the MDR-Z1000 is supposed to be Sony's top studio headphones there, much as the MDR-7520 is Sony's top studio headphones in the States (even though the cheaper MDR-7506 is more commonly seen in studios).
It's supposed to be more mid-centric and analytical, both qualities I enjoy. (I think it's also much better looking, but that doesn't matter too much.)