But did you hear them with the HA-160? The reason I ask is that the W5000 doesn't have to be paired with a tube amp in order to perform at its best as you suggest. The HA5000 amplifier that was manufactured for audio-technica to be mated with the W5000, is a solid state amplifier, which by all accounts works beautifully.
However, the W5000 has a reputation for being notoriously picky with amps. Having said that, the flagship audio-technica store in Sydney, Australia is using the HA-160 / HA-160D to drive its headphone display so I'm interested to know if there is any synergy between them and the W5000.
The PS1000 is regarded by some Grado aficionado's as being quite a departure from the John Grado "house sound" as is the HF2. I've not heard the PS1000 but I do have the HF2 and it sounds quite subdued for a John Grado headphone. Given that the HA-160 has been described as having a rather analogue approach to amplification that has been likened to a tube amp, I've been wondering if it might work well with a Grado such as the HF2 or PS1000 rather than say, the livelier RS1i.