After doing some measurements yesterday, I confirmed the PWD II draws no power from the host device connected to it’s USB input. That’s very nice as it uses it’s own internal power supply to supply clean 5V for the circuit instead of being hampered by noisy computer USB power.
However, the iPhone and iPad still cannot use this interface directly because it’s reporting a higher power draw than these devices allow, something greater than 20ma or 100ma depending on firmware version. I hope it would be possible that the reported power consumption by the USB section be lowered through a firmware update so the iPad and iPhone can be used with the Camera Connection Kit adapter directly into the PWD without a secondary hub. Technically all that is needed is the reported power consumption by the PWD USB section to be set to something very low, maybe the lowest allowed setting through the spec. This would allow devices like phones and tables (IOS and Android) to work directly connected to the PWD USB interface.
I hope PS Audio can help implement this firmware change to help make this a reality. An Ipad feeding directly into a PWD can last for an enormous amount of time and be a great music source.
Thanks!
I am elaborating around the same subject in this tread:
http://www.psaudio.com/forum/#/discussion/6050/headphone-solution
Or a little bit of custom hardware: a standard USB cable with the +5V contact removed from the B connector. No load there at all and no RFI carried into the PWD by the +5V line. I don’t know if removing the Gnd contact would improve or degrade the performance of the cable. You might experiment with a cheap cable just to see how it works.
Maybe Christopher could make a couple inexpensive custom USB cables as an experiment? 
if it works, I’d take one, perhaps 2M. 
J.P.
But it might be that the power requirement is real. In this case it is risky.
A forum member has already removed the +5V contact from a USB cable and it worked just fine with the PWD. This should also work with the NWD. I do not know what effect that removing the power lead ground contact would have, that is why I suggested experimenting with a cheap USB cable to minimize the cost of a failed experiment. The iThing may require the power connection in order ro acknowledge the device connection so cheap experimentation is still in order.
J.P.
I have a device called a short block. It removes the USB power wire as well as adding a chock . I use it and does make a small change in the sound or at least I think it does…lol.
The Hegel DAC you mention in that other post works because it reports less power draw and IOS allows it to then power up. The HRT Microstreamer also works for the same reason. The PWD actually draws zero power from the iDevice so should work other than the fact that it must report a higher consumption than the iDevice allows. A Firmware update to get around that limitation should take care of it. The HRT Microstreamer was made compatible with iDevices with a later firmware update lowering the reported power consumption.
The Hegel DAC you mention in that other post works because it reports less power draw and IOS allows it to then power up
No, it doesn't.
It reports that the power drawn is too high, this is why I mention the USB hub in the first place.
But I agree that the PWD should work 'right out of the box'
The Hegel DAC you mention in that other post works because it reports less power draw and IOS allows it to then power up
No, it doesn't.
It reports that the power drawn is too high, this is why I mention the USB hub in the first place.
But I agree that the PWD should work 'right out of the box'
Oops, I thought the point of that post was you found another device that can connect directly to the iPad, I just saw the third link was for a mini hub.
The HRT Microstreamer can work directly plugged into an iPAD with CCK without a hub in the way because it reports low power usage. The PWD II should also be able to since it doesn't use any power from the host computer.