USB Noise Update:
I received and connected the Schiit Wyrd decrapifier. The verdict...
It's a keeper. Prior to connecting, the USB noise was first noticed with the volume control set at 25% on up. Now the volume has to be cranked beyond 65% to first notice the noise. Listening through headphones I will rarely have the volume approach 50% and most often around 25% with the headphone level control set at 50%. So for all practical purposes, my problem is solved. Not being proficient at estimating db, but I'll gander a guess that I gained about 10db to 15db of USB distortion-free volume (S/N ratio.)
My suggestion to anyone with annoying USB noise, after you try a few different computer USB ports and a couple of different cables and the noise is still there, try the decrapifier though Amazon. You can return it if it doesn't work for you. But there's a really good chance it will.
Edited by Clarinet (01/27/15 12:06 PM)
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Outlaw RR2150, Definitive BP8040 speakers (2), Behringer 9 band graphic equalizer. Music sources: CDs, ripped CDs, MP3, some FLAC via desktop computer; tablets via Bluetooth receiver on Outlaw amp.