The WM-EX911 is the only metal walkman with touch control from these four. It feels similar to the metal midrange models from this era. Like the WM-EX348 it has the Auto Wind mechanism for the headphones, and is controlled by remote control. There's no other control for the basic functions than the remote, so if it's broken like this one you can no longer control the walkman. The WALKMAN logo is embedded in the transparent window, a nice twist you don't see so often.
All these 4 models still have a normal headphone jack, so you always have a choice to use either the built-in headphones or an external one. I like the idea of the built-in headphone a lot, even though I'd probably never would have bought these myself as I always prefer using higher quality headphones. I assume the WM-51 was the first model to offer this feature (can somebody confirm) and I still like the WM-51 best of all these models. I'm sure there will be more than these four models, Emiel already mentioned the WM-EX922 as the fifth, please add the other models with built-in headphones.
