Well, this is a surprise...
Indeed, and the reason why the Z1R has quite mediocre bass for a £1700 headphone. Its sub-bass distortion is quite high. I suspect the magnet system is far too weak to control the 70mm transducer it possesses, resulting in a significantly weaker slam and tautness in the very lowest registers compared to the TH900. Its also inferior in clarity and instrument separation, particularly with dense acoustic music and live performances. But its a nice looking headphone with a very wide sound stage, good for wowing casual, uncritical listeners.
-I didn't think this was a discussion page for uncritical headphone listening. I thought there were other forum pages here to deal with such gear. (Chuckles) I guess it's a good idea I didn't splurge on this "lousy" set of cans. Oh, I'm on the floor with that account on the Z1R you guys all love.