Oh noes, I always use my external hard drive and USB mouse... so I don't think the D4 suits my style. Any other recommendation that is comparable to the D4?
If you have your devices daisy-chained together thru a hub, you will share the single 500ma from the port in your computer that the hub is plugged into, but if you have the D4 plugged into its own USB port on your computer, it will receive the full 500ma.
All of my devices used by my computer are USB, but I never share the USB port used by my DAC/Amp.
The USB-fed power supply in the D4 is pretty well filtered and I have never gotten any noise or other artifacts when the D4 is plugged into its own USB port.