I know it’s probably not the thing to do but I can find no instruction in the user guide to say not to do it. I found that I can charge my phone using the qu-drive USB port. Should I desist from this activity? 
I would not recommend it, it is possible that the USB port may not be able to supply enough current (amperage) to charge the phone, if something would be damaged, it would be the port supplying the power, not the device taking it.
At least in the case of a USB port.
Yes I agree, I’m not planning to do this in future but I couldn’t help myself but plug phone in very briefly to see if it charged, Qu-drive is still working BTW! If it is an issue then I guess a warning in the user guide might be a useful addition.
Cheers,
David
Normally a USB port should have some sort of overcurrent protection and should provide up to 500mA regularly. The iThings implement a special “protocol” (some resistors, to be specific) to handshake with the host (in this case the Qu) for more current (faster recharge).
If designed properly (which I somewhat expect from A&H) it should not be a problem to connect an iThing for charging.
There are several spinning HDDs around which pull more than the allowed 500mA from the USB port and the Qu nicely deals also with those.
I personally won’t fear to misuse the QuDrive-Port for charging, but some official comment would be nice though.
It does not say in the use manual that you should not use your Qu to hammer in nails either…
LOL, true!
I’d be more concerned about the large amount of rf emitted by the phone, and the effect on amps and speakers should you get. Call with the phone that close to the desk (charging or not)