Tascam Us 122, portable, vs powered? Options

[johnnyboy]

i noticed the tascam us 122 is a portable device, which means it draws power off the computer. Does this mean that it will have a lower quality recording than a device that has its own power source. Also, in the book, it says that you have to be careful about running other usb devices on your computer, such as the printer, since it will draw power from it and cause sound issues. I looked at the review of it and didnt see any mention of this issue. I was looking at the M audio audiophile usb, but it doesnt have xlr inputs nor a phantom power source for condenser mikes. Is there something like the us 122 out there that has its own power source, or is this even an issue?