I just built up my new machine based around the Z87-Plus w/ i5 4670k, 16GB RAM, Asus GTX760 OC, and a new SSD for system drive. I loaded Windows 7 Professional 64bit with no issues. Went through and installed all the drivers from the disks and (seemingly) had no issues. I started out using the onboard Realtek audio connections with my Logitec z560 4.1 speakers (old!). I noticed something was off immediately...I went to the Realtek software to test the speakers and what I found was that nothing was coming out of the Left or Rear Right speakers, but I would get sound out of the Right and Rear Left speakers. After fiddling around, I decided to try installing my old Sound Blaster Audigy in the PCI port. Did that, disabled the onboard audio, got the WIN7-compatible drivers loaded for the Audigy, and finally got sound through the speakers. Much to my dismay, I was having the same issues as I was with the onboard chip! I messed around some more and found some other interesting things: testing in stereo mode, "Left" would produce a sound in the right speaker, and "Right" would produce a much louder sound. I'm at a loss....any help or guidance would be greatly appreciated!