Today I just picked up a iFi usb micro power supply to try with my teac ud-501 computer rig. My initial impression after about an hour or two is that the micro is definitely an improvement over the standard usb feed from my computer. I am using the teac ud-501 to feed my emotiva airmotiv 5 active speakers on my desk top. I use the passive attenuators on the airmotiv 5s to control the volume given the lack of a preamp function on the teac ud 501.The isolation of the usb signal from interference and the dirty power from my desktop computer power supply does seem to make a difference . Of course I only have a couple of hours on the iFi micro so it is to early to make any permanent judgement about the effect of the separating iFi micro power supply. But already the benefit of a separate power supply seems to have a noticeable effect on the sound of my desk top set up.
For anyone looking to improve the sonics of their desk top set up you might want to investigate the IFi micro power supply . It does seem to make a noticeable improvement in the sound reproduction of your desk top set up. My next stop is to investigate the iFi Gemini usb cable. While it is not cheap (it actually costs more than the iFi Micro usb power supply in a 1.5 meter length) after reading about the combination of the power supply and the usb cable the resultant sound may actually be reasonable in lite of the costs of some of the higher end usb cables out there. I can see the possible improvement from separating the signal from the power. It should be interesting to see what it does for my teac ud-501.