I have a basic P6T and never had any problems with sleeping. I seem to remember something about one of the variants, but it has been too long. Possibly you could find something on the net. I will try to compare the boards to see if I notice something that might be relevant.
You are changing so many things so quickly, I cannot keep up. I would just run a basic setup with no USB hub and see if you can get it to work.
Someone in another thread stated they found a task checked in the Task Scheduler but did not show up as a last wake entry. You might check yours by opening Task Scheduler, Microsoft-Windows-Multimedia. See if SystemSound is listed and and under the Conditions Tab, see if "Wake the Computer to run this Task" is checked. This is not a default setting for Windows, but for some reason his was checked. When I checked it on my system, it did keep the system awake, but did show up on the lastwake report.